I think the flash is a bit too harsh, especially because there is a wall in the background.
Are you usign the flash on- or off-camera? Looks like it's on-camera based on the shadows - try to get the flash working off-camera and the shadows will start to work better in your favour

Also, you might see about trying to slow down the shutter speed to give it a bit of slight motion blur effect - remember your flash will freeze a frame of motion, but you'll get slight light trails (you'll need to set your flash to second curtain sync or else it'll look like people are moving backwards

).
Hope that helps.