How to target an MC in a mask layer?!

Hi All.

I have these 2 lines of code:

_root.pattern_cntr1.background_A.colorTo(0xB1273F);
_root.pattern_cntr2.background_B.colorTo(0xB1273F);

The second cntr isn’t changing colour and I now see that this is because it is in the mask layer. However I don’t know how to target this differently! I’ve tried searching for similar issues but unable to find something.

Any guidance would be greatly appreciated.

Claire