Dynamic Text Box inside Movieclip

I have a dynamic text box called “desc_txt1” which is inside a movieclip called “thumbScroller”

i cant get it to display the text from the xml file, but if i put the dynamic text box on the main time line then it works…

heres what i have:

on maintime line

thumbScroller.desc_txt1.text = description[p];

and have tried

_root.thumbScroller.desc_txt1.text = description[p];

neither work, does anyone know whats going on?