Exporting FBX file from blender to XNA

I imported an object file into Blender, and I added an armature to the character and parented the armature to the mesh… I then assigned the vertices to ONE bone, but when I try importing into XNA it gives me this error…

Error normalizing vertex bone weights. BoneWeightCollection does not contain any weighting values

I have been looking all over the web for a solution to this but I already painted the vertices to ONE and still same error…

COuld you guys possibly lead me to a solution this problem it would be greatly appreciated thank you…

i tried attaching the blend file associated with this issue but the upload gave me error…