Okay, so I've seen the other answers to this here in Blender Exchange. However, as far as I can figure out those textures were not saved when created in texture paint mode.

I added an external texture to my object:

1 http://s13.postimg.org/9fyq9iywn/257.png

...then I switched to texture paint mode and the texture changes to a complete black texture:

2 http://s17.postimg.org/ox986g13z/258.png

However if I switch back the texture while in texture paint mode it still keeps my object black:

3 http://s4.postimg.org/trzru8x65/259.png

4 http://s3.postimg.org/c251tvewj/260.png

Is this a lighting problem? Or am I not importing the external image correctly? I have tried packing/saving the image after importing it and putting it on my UV Map and then switching to texture paint mode, but it still occurs.