I actually think you have the angle of the first light source right. It's "in front of" the signature, shining onto it. (You should widen it though, so it's hitting the "void" of sig to the right of him)
However, looking at the arm that's left to us, there's two more light sources: one behind the arm and one to the left of the hand. Account for these.
He is also very much in a void. I get a vague sense of "deeply underwater", but not even that. Anchor him more. The background needs to "hold" him. If you fix the lighting you may accomplish that without further effort, or you may have to add a gradient to the background.