Progress of a movie (not a preloader)

I am simply trying to display the frame number of a movie as it plays.

I have a dynamic text box with a var(iable) called framenum. I use an off stage movie clip with the following code attatched to the movieclip:

onClipEvent (enterFrame) {
framenum = _currentframe;
}

(I believe that you don’t need to target the movieclip if the code is associated with that clip, although I have tried this as well)

Why doesn’t this work please ?

Thanks