Sun Lamp doesn't show when background lighting is used Situation: I'm creating an ocean scene. I have an ocean with reflecting material. Therefore, I used a picture on a plane as to have the background image reflected on the ocean.

Problem: However, a sun lamp doesn't seem to work when rendered with the background plane. When I just rendered the sun lamp and the ocean, the ocean is lighted. However, with the background image rendered, the sun lamp doesn't seem to show up. (I had tried increasing intensity and changing color to bright purple first). How could I have the lamp reflected on the ocean together with the background plane on the scene?
Here's the blend file.


Rendering only ocean and light


Rendering with ocean, light, and background image (there should be a purple light, but it doesn't show)
Your plane is casting a shadow. moving the sun lamp will not help since unlike point, the sun lamp casts global lighting. To fix this, move your sun into the same layer as the water and select This Layer Only