Bone heat weighting: failed to find solution for one or more bones

[Suki Hirano]

I'm trying to learn the basics of rigging in Blender 2.73. What I do is basically just position an object, select object then select armature, then ctrl+P with automatic weights. I get the error "Bone heat weighting: failed to find solution for one or more bones" whenever I try to rig very small objects to the SL body. For instance if I try to rig something like a belly piercing or pasties, it'll throw that error, but if I simply create a cylinder directly in Blender, put it on the body, and rig that, it won't throw an error. I got the SL skeleton from SL wiki. I'm guessing it's because Blender doesn't know which bone I want to rig the small object to? Anyone know how I can fix this?