Sample Button dynamic return address

[Sans84]

How to specify a return address for a button if the address is dynamic (constantly changing)?

I already tried:

<input type="hidden" name="cancel_return" value="http://simple.com/error">
<input type="hidden" name="return" value="http://simple.com/success">
<input type="hidden" name="return_url" value="http://simple.com/success">

but it did not give a result