Cube 2 requires individual meshes to be indicated by OBJ groups, not OBJ objects, which is probably not default behavior for SketchUp.
Nieb's simple tree-sprite model demonstrates proper form for getting your model displayed.

I don't know about SketchUp, but Blender OBJs need to be modified slightly.
The beginning of each individual mesh is indicated by "o MESHNAME". Remember that name, then find the next "usemtl" line, and above it add "g MESHNAME". Load into Cube 2 with appropriate obj.cfg (Nieb's tree example here. All you probably need is objload, objskin, and maybe mdlscale.)

Thanks!

Ive been using sketch-up for quite some time. pro 7 has export to 3dsmax, maya, blender ect. so your going to need sketch-up pro7 and export it to either 3dsmax or blender then mesh it from there. as far as im concerned texturing and rendering in sketch-up sucks. I am currently making models for MisanthropX "crush" project and I am starting the basic models in sketch-up and then exporting them to 3dsmax to texture and mesh, then exporting to blender to make the final tweaks for the cube engine.