Problems with jMonkey and Collada

I created a simple model (a cube) in Blender and exported it to both Collada and MD2 formats. I can get both models to load and appear, but the Collada one has strange culling effects (it acts like it it's a high-level node, making big chucks of my level disappear when it's out of view). For now, I'm going with MD2.

I found the Blender 3D Noob to Pro tutorial indispensable.

 

By the way, I couldn't get either to work in jME until I had performed UV mapping on my model, which apparently gives the information necessary to apply textures. Blender doesn't let you export to MD2 until this is done, whereas it let me go ahead and create a Collada file that loaded but displayed a messed up model in jME.