[Zope] How to use multiple selection variable.

Hi, I have set created a multiple selection varible in the property tab of my object. I am having a hard time displaying it. approver_list is the name of my multiple selection. I attempted to display the list by using <dtml-var approver_list> in my document but it didn't work. I got "[]" in return. May I know what I have done wrong that it only display "[]". Thanks for your help. -Charlene