Ok, here's my new problem.
Everything renders fine , but as soon as I try to render a textured cube, I get a crash, the error is:
"An error occurred while preparing to draw. This is probably because the current vertex declaration does not include all the elements required by the current vertex shader. The current vertex declaration includes these elements: SV_Position0, NORMAL0"
I tried using a custom shader as well, but I get the same problem.
If I remove "effect.TextureEnabled = true", everything is fine, except there is no texture rendered of course.
Anybody can help?