Errror when trying to use NLexpression

[YDHsieh]

Hi guys, after I try the code below, I got an error:

Code:

function solveMPC(l,w,n,m,T,z0,zT,zmin,zmax,umax,dt)
    mpc = Model(solver=IpoptSolver(print_level=0))
    @defVar(mpc,  zmin[i] <= z[i=1:n,t=1:T+1] <= zmax[i])   
    @defVar(mpc, -umax[i] <= u[i=1:m,t=1:T] <= umax[i])     
    @setObjective(mpc, Min,
    sum{(z[1,T]-zT[1])^2+(z[2,T]-zT[2])^2+10*(z[3,T]-zT[3])^2+(z[4,T]-zT[4])^2+(z[5,T]-zT[5])^2+(z[6,T]-zT[6])^2+(z[7,T]-zT[7])^2,t=T-7:T})
    @NLexpression(mpc, af[i=1:T] ,atan((z[5,i]+l*z[6,i])/z[4,i])-u[1,i] )
    @NLexpression(mpc, ar[i=1:T] ,atan((z[5,i]-l*z[6,i])/z[4,i]) )
    @NLexpression(mpc , Ffy[i=1:T] , Caf*af[i])
    @NLexpression(mpc , Fry[i=1:T] , Car*ar[i])

   for i=1:T
      if z[4,i] == 0
      return af[i]=ar[i]=0
      end
   end 
    # Link state and control across the horizon
     for t = 1:T
        @addNLConstraint(mpc, z[1,t+1] == z[1,t] + dt*z[4,t]*cos(z[3,t])-dt*z[5,t]*sin(z[3,t]))
        @addNLConstraint(mpc, z[2,t+1] == z[2,t] + dt*z[4,t]*sin(z[3,t])+dt*z[5,t]*cos(z[3,t]))
        @addNLConstraint(mpc, z[3,t+1] == z[3,t] + dt*z[6])
        @addNLConstraint(mpc, z[4,t+1] == z[4,t] + dt*(u[2,t]-Ffy[t]*sin(u[1,t])+M*z[5,t]*z[6,t])/M)
        @addNLConstraint(mpc, z[5,t+1] == z[5,t] + dt*(Fry+Ffy[t]*cos(u[1,t])-M*z[5,t]*z[6,t])/M)
        @addNLConstraint(mpc, z[6,t+1] == z[6,t] + dt*(l*Ffy[t]*cos(u[1,t])-l*Fry[t])/Iz)
        @addNLConstraint(mpc, z[7,t+1] == z[7,t] + dt*((Ffy[t]+Fry[t])/(M*z[4,t])-z[6,t]))
     end

    # Initial conditions
    @addConstraint(mpc, z[:,1] .== z0)
    # Final state
    #@addConstraint(mpc, z[:,T] .== zT)
    # Solve the NLP
    solve(mpc)
    #return getValue(u[:,0]), getValue(z[:,1])
    return getvalue(u), getvalue(z)        
end

and the error:

ERROR: LoadError: Unexpected vector JuMP.NonlinearExpression["Reference to nonlinear expression #451", "Reference to nonlinear expression #452", "Reference to nonlinear expression #453", "Reference to nonlinear expression #454", "Reference to nonlinear expression #455", "Reference to nonlinear expression #456", "Reference to nonlinear expression #457", "Reference to nonlinear expression #458", "Reference to nonlinear expression #459", "Reference to nonlinear expression #460", "Reference to nonlinear expression #461", "Reference to nonlinear expression #462", "Reference to nonlinear expression #463", "Reference to nonlinear expression #464", "Reference to nonlinear expression #465", "Reference to nonlinear expression #466", "Reference to nonlinear expression #467", "Reference to nonlinear expression #468", "Reference to nonlinear expression #469", "Reference to nonlinear expression #470", "Reference to nonlinear expression #471", "Reference to nonlinear expression #472", "Reference to nonlinear expression #473", "Reference to nonlinear expression #474", "Reference to nonlinear expression #475", "Reference to nonlinear expression #476", "Reference to nonlinear expression #477", "Reference to nonlinear expression #478", "Reference to nonlinear expression #479", "Reference to nonlinear expression #480", "Reference to nonlinear expression #481", "Reference to nonlinear expression #482", "Reference to nonlinear expression #483", "Reference to nonlinear expression #484", "Reference to nonlinear expression #485", "Reference to nonlinear expression #486", "Reference to nonlinear expression #487", "Reference to nonlinear expression #488", "Reference to nonlinear expression #489", "Reference to nonlinear expression #490", "Reference to nonlinear expression #491", "Reference to nonlinear expression #492", "Reference to nonlinear expression #493", "Reference to nonlinear expression #494", "Reference to nonlinear expression #495", "Reference to nonlinear expression #496", "Reference to nonlinear expression #497", "Reference to nonlinear expression #498", "Reference to nonlinear expression #499", "Reference to nonlinear expression #500", "Reference to nonlinear expression #501", "Reference to nonlinear expression #502", "Reference to nonlinear expression #503", "Reference to nonlinear expression #504", "Reference to nonlinear expression #505", "Reference to nonlinear expression #506", "Reference to nonlinear expression #507", "Reference to nonlinear expression #508", "Reference to nonlinear expression #509", "Reference to nonlinear expression #510", "Reference to nonlinear expression #511", "Reference to nonlinear expression #512", "Reference to nonlinear expression #513", "Reference to nonlinear expression #514", "Reference to nonlinear expression #515", "Reference to nonlinear expression #516", "Reference to nonlinear expression #517", "Reference to nonlinear expression #518", "Reference to nonlinear expression #519", "Reference to nonlinear expression #520", "Reference to nonlinear expression #521", "Reference to nonlinear expression #522", "Reference to nonlinear expression #523", "Reference to nonlinear expression #524", "Reference to nonlinear expression #525", "Reference to nonlinear expression #526", "Reference to nonlinear expression #527", "Reference to nonlinear expression #528", "Reference to nonlinear expression #529", "Reference to nonlinear expression #530", "Reference to nonlinear expression #531", "Reference to nonlinear expression #532", "Reference to nonlinear expression #533", "Reference to nonlinear expression #534", "Reference to nonlinear expression #535", "Reference to nonlinear expression #536", "Reference to nonlinear expression #537", "Reference to nonlinear expression #538", "Reference to nonlinear expression #539", "Reference to nonlinear expression #540", "Reference to nonlinear expression #541", "Reference to nonlinear expression #542", "Reference to nonlinear expression #543", "Reference to nonlinear expression #544", "Reference to nonlinear expression #545", "Reference to nonlinear expression #546", "Reference to nonlinear expression #547", "Reference to nonlinear expression #548", "Reference to nonlinear expression #549", "Reference to nonlinear expression #550", "Reference to nonlinear expression #551", "Reference to nonlinear expression #552", "Reference to nonlinear expression #553", "Reference to nonlinear expression #554", "Reference to nonlinear expression #555", "Reference to nonlinear expression #556", "Reference to nonlinear expression #557", "Reference to nonlinear expression #558", "Reference to nonlinear expression #559", "Reference to nonlinear expression #560", "Reference to nonlinear expression #561", "Reference to nonlinear expression #562", "Reference to nonlinear expression #563", "Reference to nonlinear expression #564", "Reference to nonlinear expression #565", "Reference to nonlinear expression #566", "Reference to nonlinear expression #567", "Reference to nonlinear expression #568", "Reference to nonlinear expression #569", "Reference to nonlinear expression #570", "Reference to nonlinear expression #571", "Reference to nonlinear expression #572", "Reference to nonlinear expression #573", "Reference to nonlinear expression #574", "Reference to nonlinear expression #575", "Reference to nonlinear expression #576", "Reference to nonlinear expression #577", "Reference to nonlinear expression #578", "Reference to nonlinear expression #579", "Reference to nonlinear expression #580", "Reference to nonlinear expression #581", "Reference to nonlinear expression #582", "Reference to nonlinear expression #583", "Reference to nonlinear expression #584", "Reference to nonlinear expression #585", "Reference to nonlinear expression #586", "Reference to nonlinear expression #587", "Reference to nonlinear expression #588", "Reference to nonlinear expression #589", "Reference to nonlinear expression #590", "Reference to nonlinear expression #591", "Reference to nonlinear expression #592", "Reference to nonlinear expression #593", "Reference to nonlinear expression #594", "Reference to nonlinear expression #595", "Reference to nonlinear expression #596", "Reference to nonlinear expression #597", "Reference to nonlinear expression #598", "Reference to nonlinear expression #599", "Reference to nonlinear expression #600"] in nonlinear expression. Nonlinear expressions may contain only scalar expressions.

So, it means that the format about NLexpression:
@NLexpression(mpc , Ffy[i=1:T] , Cafaf[i])
@NLexpression(mpc , Fry[i=1:T] , Carar[i])
maybe the two above, cannot be accepted ?

and the format like:

for i=1:T
if z[4,i] == 0
return af[i]=ar[i]=0
end
end

can be accepted or it should be wrote in constraints ? or another way?

Please and thanks！