What version of Blender are you using? I've not had a chance to test any of the scripts with 2.63 so that may be an issue.
But to address your problem, you need to select the objects to be exported
, mesh first then Armature last
(the Armature needs to be the lighter colour indicating it's the 'active' object). The Object must
have a material, texture and UVW map, you can't export an 'empty' mesh. Read the "how to export MD5
" for some basic info, essentially though the model needs to be properly prepped.