Ah, then yes we have the same problem. With that mesh you have there, do you want the decal completely covering it? or do you want some light to show through? or maybe parts of the decal to cover parts of it? I would say if u want it completely covered then just take off the emissive entirely, if u want some light to show through maybe try a very small value(like very small) in the multiply node so that some of the decal shows over it, yet that could make it grayish. Test it out and post some pics