[Zope] variable

Hello, I have a line of code which is meant to tkae an integer variable (vchildren) passed to the page through a hidden form. I have a line of code which goes: <dtml-var "_.chr(vchildren+97)"> and it returns an error message of which this is part: File C:\Program Files\ZopeJosh01\lib\python\DocumentTemplate\DT_Util.py, line 335, in eval (Object: _.chr(vchildren+97)) (Info: vchildren) File <string>, line 0, in ? TypeError: (see above) The value of the variable is 0 josh