Jscript error on conditional workflow rule.

Hi All,

I am working on a workflow for a client in CRM for enrollment to a club. As part of the enrollment process, I want to place a conditional rule on whether or not the client has paid a deposit to the club so I used the following javascript:

if(confirm("Has member paid deposit?")){Valid=true;}else{Valid=false;}

When I go to test the workflow and run the rule I get the following error:

Workflow Java Script jscript error: Object expected Line: 1 Char: 6597

I guess this means the CRM doesn't like my javascript but I can't see what is wrong with it - does CRM not accept user input through Javascript?