[Zope] Problem using SQL Example from the Zope Book

Hi there, I try to build the examples given in chapter 10 When I try to access a ZSql method passing it a parameter like this http://localhost:8080/employee_by_id/emp_id/42 where the parameter name is emp_id and the value 42 I get a "not found" traceback I have to use http://localhost:8080/employee_by_id/manage_test?ClientID=12 why does it not work like the Book sugests? thanks for your time Robert