Combined Two objects now i can no longer texture paint I created a head, and a body, I had a uvmap for the head and body seperately, and combined them when i combined the meshes into one.  I have two materials, and a combined uvmap, and the model looks fine.  I have to two associated diffuse images associated with the head (which I can still texture paint) and two associated with the body that I can no longer paint on.  What's going on? I didn't find a solution with related asked question, none where a perfect, I tried their solutions to no avail.
We really should compile a trouble shoot of all the answers in one place, the problem was my model was not completely symmetrical.  Instead of allowing me to paint, the paint function just gets turned off all together, you have to turn symmetry off in my case.