I've been working with the Collada format lately, and thought I'd take a swing at this one.
I compared a cylinder exported in AC3D against the exported cylinder provided in the above link. The fundamental difference is that the cylinder in the link above uses <triangles> to describe geometry, while AC3D uses <polylist>. Both formats look syntactically correct, however, and I can find no problems in the AC3D export --- I was also unable to get any other Collada importer to break when loading an AC3D Collada file.
I've attached a cylinder exported from LightWave -> Collada - can you see if that one imports? ( NOTE: I had to rename it to cyl_lw.dae.txt - you can rename it to cyl_lw.dae )
If the attached file imports, then we can more easily compare the AC3D and LightWave files, since they both use the same geometry descriptors.