[Zope] How to use multiple selection variable.

[CHOY,CHARLENE (HP-Boise,ex1)]

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