Execute AS3 in external SWF

Hi all,
I am loading an external SWF from the same domain (localhost at the moment) into my flash movie (Flash CS4 AS3).

The movie plays ok,
I can insert text in a dynamic text box of the external movie from the main movie.

But…
The Actionscript in the external movie wont execute?!

How can I make it execute the AS in the external movie?

It actually works when testing in Flash CS4, but not in my browsers.
Thanks
JR