how can i pause FLVplayback in as3 ?

Question

(Event.ENTER_FRAME,myFunction); function myFunction(event:Event) 
{ 
if (fk.playheadTime > stopTime) 
{ fk.pause(); } 
} 

i pause my video at stoptime it works but then when i press the play button it doesn't work.i guess the problem is my code's place.as you can see i write it in enter_frame event.how can i solve this problem?thanks for any help.