[Zope] Passing variable to a python script

Hi, I'm trying out python scripts and can't get the variables posted from a form accross. I'm calling the script from a dtml method via <dtml-var python-script-name> but keep getting "unknown variable" as the error .. it's a simple script that adds two numbers together (x = first_number + second_number) and first_number, second_number are from the form. The show answer method can display both variables (<dtml-var first_number>) I'm using python 2 (compiled zope from source) is this the problem? if it is, can I run python 2 with pyton 1.52? Regards, Mehmet