Greetings, I'm not having success with the Zope Book ch 3 script example. First, I've noticed it has the formula wrong in the script. Original: i = interest_rate * periods # (don't I wish my bank would do this :) i = i + 1 n = periods * years return pow((1 + i), n) * principal # already added 1 to i above Correct: i = interest_rate / periods i = i + 1 n = periods * years return pow(i, n) * principal BUT, even with that, submitting the form returns an error of "not enough arguments: expected four, got 0". In the Zope manager, on the editor for script calculateCompoundingInterest, I have entered principal, interest_rate, periods, years in the parameters field. The form page has these same params specified as input fields; I don't know much about Zope but I'd guess that Zope should understand that each named input field is a parameter name, accompanied by its value. So what is going wrong? Does the script itself need to look more like a regular Python function, ala 'def calculateCompoundingInterest(principal, interest_rate, periods, years):' ? Or is <dtml-var calculateCompoundingInterest> not the correct way to call a script from a page? TIA, Robert Boyd