I can't run the Flow Simulation

[NineFive2]

I drew a flying wing in Solidworks 2008 to test the lift and drag, but when I click at the flow simulation, it said that I haven't close holes and spaces in my model although I didn't draw any hole.
Does anybody have idea to fix this? I have to test the lift and the drag of this model

[tnik]

check your surfaces.. It sounds like some of them aren't joined.