Place tab button

Hi, I am using designer 2.007 and I want to place tabs on my design and I cant get it to become active... I would appreciate it if some one could tell me under what conditions it becomes active... I know I have used it before, but no mater what I try I cant get the button to become active.
Thank you.

After drawing all of your tab lines, select all of the lines and then the add tab tool should become active.