Paint Brush and Paint bucket tools

Help needed!!! When I use my paint brush or paint bucket tools it only paints grey. I don't have any masked layers or any smart layers. I've tried painting on a new layer and it still is painting grey. I've reset both tools and I've made sure the color I want is set to the foreground and  it's still painting grey. The images I'm editing were imported as png files, could that be the problem?