Is there a secret setting that keeps me from painting textures I am sorry if there is already a post like this but the only things I've seen are tutorials and explanations on how to set-up the start file or something similar for texture painting. 
My problem is that i can't bring it to work no matter what. I've made sure that I am on the right paint slot, UV-Map and object. It all doesn't work. The weird thing is that this only occurs on my project so I believe there is a hidden setting or something that I must've clicked by accident that keeps me from progressing further. Is there a way to reset only the project settings? Without messing with my global preferences?

I have uploaded a video on Youtube which shows what I mean.
Youtube Video
It was a really simple solution - change Blend mode of the brush to Add (in this case) instead of Color and remove texture mask with empty texture from the Texture rollout.