Looks like the light source is from upper right...you might want to adjust the shadow.

Ah - I used a portable flood light

Just flip horizontal the background, and the lights will be in the right place. The perspective of the shadows have to work with the light source. The image will look better if you do so.

Thanks - I've tried to reverse the background now

The shadows shoud be in the front. As a suggestion for your future work. Whenever the light source is behind or to the sides of an object, the shadow will always be on the back of the light, if your object is behind the light, it should be darker with a shadow at the front. If your light source comes from the right side, your shadow should be to the left, and viceversa if light comes from the left side, your shadows will be to the right. But try to work with perspective.... It is kind of difficult to understand, but if you check this link... you will understand.

Link: http://www.youtube.com/watch?v=oajh9Lgm8FE

Link: http://www.youtube.com/watch?v=60vHSFlKu3c

Here are two different ways to cast your shadows....hope this help!