Why can't i place a Dynamic Text Box inside a MC

i need to put a Dynamic Text Box (or TextArea) inside a movie clip so i can create a mask.
i am loading xml text with CSS styling into the text box
however with a TextArea -it wont show the text at all
with textbox - if i embed the text it shows the text but not the styling.

i cannot find a workaround for this anywhere.
thanks
Dan