I think it needs more contrast. The easiest 'zing' at this point would be some drama. It would help give it a focal area as well. Here's a quick 15min photo-manipulation of pushing the contrast and adding some texture to the back wall.

The texture on the wall would push the fabric forward via a contrasting texture, instead of being smooth on smooth Some stronger lighting would guide your eye to the upper surface of where the cloth drapes over the brick's corner. Here I've only raised the forward highlights just a bit, darkened the mid-tones of the background, and punched the foreground shadows to get a more contrast driven 'pop.'