Hi, I'm new to Zope and am working through the Zope book examples. I'm stuck on the compound interest rates example, found in Chapter 3 under the "Using Scripts" section. I can't get the python script in that example to work, using Zope 2.3.0. I copied the entire example into Zope and tried to exercise it by going to the "View" tab on the interestRateForm DTML method. I typed in valid integers for the 4 parameters and pressed the "Calculate" button. I got: ErrorType: TypeError Error Value: not enough arguments; expected 4, got 0 So, to simplify, I went directly to the Python script "calculateCompoundingInterest" , added string.atoi lines to avoid "can't multiply sequence with non-int" type errors on input, and tried to run the script directly via the "Test" tab. Now I get: Error Type: TypeError Error Value: not enough arguments; expected 4, got 3 Here's my python script (I do have the 4 parameters separated by commas in the script's "Parameter list" area): """ Calculate compounding interest. Accepts four parameters, "principal", "interest rate", "periods" and "years". """ # I added the next 5 lines so could test this script directly via Test tab. import string principal=string.atoi(principal) interest_rate=string.atoi(interest_rate) years=string.atoi(years) periods=string.atoi(periods) i = periods * interest_rate i = i + 1 n= periods * years return pow((1+i), n) * principal Thanks for any help. -Linda