Baking/UV problems

I am trying to bake the tangent normals of an object onto an image i created for it but instead it bakes over a color map for the same object. I made sure that the right image was selected but it still will not bake onto it.

I am trying to bake the normals from a high-poly object onto a low-poly version of the same object. The problem is that it bakes the normal map over the wrong image (in the UV/Image editor).

Where have you selected it? In the uv image editor? Did you do it while in edit mode with all faces selected?