Scrollpane won't scroll

I have a scroll pane, and its content path is ‘text_mc’

text_mc is a movie clip with a bunch of dynamic textboxes in it, all of which load text from an external source.

Each dynamic textbox is coded so that it will resize to fit the text it is loading into it without needing to scroll that particular textbox, and each textbox is also coded to be moved into place with all the other text boxes when they are all resized (to avoid gaps)

The problem I am having is that the scroll pane will not have a scrollbar even though the movieclip (text_mc) is much larger than the pane. Is this because I am loading the text after the pane is made, and is there any way for me to get around this?

Scrolling is enabled on the pane.