Parametr in URL

[magneto664]

Hi, is possible to use parametr in urls for example in button i have a place for url= and i try insert on this place a custom_field where I save a url so i add

[symple_button url="[field custom_field]" color="red" size="default" border_radius="3px" target="self" rel="nofollow" icon_left="" icon_right=""]Download[/symple_button]

And I get error:
Please enter a valid URL and content for your button.

tnx