Calling a function to change frames in an mc on root timeline

Hi all

I have created a function on the root timeline, to be called at a certain point (when the character is on a certain frame and so is the certain item, he loses a life)

So, the lives_mc advances frame by frame to show lives being lost.

heres the function

 function loseLife(){
     if(_root.lives_mc._currentframe=1){
          _root.lives_mc._currentframe=1
     }else{
          _root.lives_mc._currentframe+=1
     }

} 

And here’s how it is being called

 _root.loseLife();  

However I can’t get the lives_mc to move… any ideas?