[Zope] keyError problem when displaying string values of a Z SQL Method

Hi, I strictly followed the explanation on ch 10 of the zope book. Kindly, point out what i am doing wrong here. <dtml-in list_all_employees> <li><dtml-var emp_id>: <dtml-var firstName> <dtml-var lastName> </li> </dtml-in> because i keep getting this error Error Type: KeyError Error Value: firstName but each time i removed the <dtml-var firstName> the same type error displayed for lastName and finally, when i removed both the <dtml-var firstName> <dtml-var lastName> it displays the the list of emp_id for me correctly. Regards. kamal