Masking dynamic content?

[robmarston]

I'm loading images into an otherwise empty MovieClip called container_mc using UILoaders and spacing them horizontally. I also have the image names as TextFields below the images all within the container.

I'm masking the container clip using the following syntax:

container_mc.cacheAsBitmap = true;
mask_mc.cacheAsBitmap = true;
container_mc.mask = mask_mc;

This USUALLY works, but for some reason when I load over 20 images into the container -- the mask no longer works. At first it appears as though it's working but then the text disappears and when I mouse over the images to scroll them horizontally, the mask (which is magenta) appears and disappears -- flickering strangely.

Should I be caching? I was under the impression I had to for the dynamic text to show up. Maybe it's the where I placed the code (load-order)?

I've been working for hours and I can't seem to fix this...

Any suggestions?