Changed properties of planets, other orbits unaffected. Is it calculating anything?

[hughsheehy]

Hi
I got it running on my local machine. It looks great!
However, when I changed Venus to be (for example) in orbit immediately inside Earth and to be 1000 times heavier, only venus moved. I expected that earth's orbit would be affected. But earth continues without any change. Is the system calculating anything? The code looks as if it is, but then earth's orbit should be significantly affected.
H