f-in maya 8.f-in 5 f-in 3d paint

rooster

for some reason every time I try to paint to the colour channel in 3d paint now, it assigns to a f-ing transparency channel instead

I want to paint over an existing image in the colour channel, which it normally will load into 3d paint and allow me to paint over. but for some reason it has started just throwing me to the transparency channel where it gives me a nice big black map to start painting on.
FARGH

rooster

edit: sort of got a work around by plugging the transparency file into the diffuse as well..
i'd really like to fix the problem tho