SWC Import MC as Modal Popup?

[mrpoptart]

All right here goes:
I have a swc that contains a movieclip typed as mx.flash.UIMovieClip

I then use that movieclip's linkage class as a new instance in Flex

then, I attach that instance to a popup manager

all of this works great, but I can't get the modal (background blurring) to work properly.

Any suggestions?

var about:AboutPopup = new AboutPopup();
about.close_mc.addEventListener(MouseEvent.CLICK, aboutClose);
PopUpManager.addPopUp(about,gui,true)
PopUpManager.centerPopUp(about);

Thanks,
Morgan