Can't erase or draw on layers - help!!!

Hi

I have a simple image made up of 3 layers, all unlocked.

The eraser and brush tools have no affect on the layers. It's weird, because they were working yesterday on the same image.

Any ideas what I have done to make this happen?

Cheers

CM

have you changed the "color mode" ?

several things don't work when you are in "indexed" color mode.