Referecing main movie variables inside an external swf

I’m having some issues referencing variables in the main movie.

On the 1st frame of the main movie I have: var testvar=“testing123”;

On the main movie I have a movieclip with an onRelease event handler that is defined with:


Slidwshow.swf contains:

trace("From the main movie: " + _parent.testvar);

however the trace statement prints “undefined” instead of “testing123”

Any ideas why?