I replastered the walls couple of month ago, there was a what it seemed like a damp patch on the wall. After lots of inspection we could not find out what was causing it. I used stain block paint and it seemed to work. Now I wish to paint the walls with emulsion. I already have applied a mist coat, but the patch where I have used a stain block does not look ling ke its blending properly with its surrondings. Can you please advice me on how to remedy this problem.