Custom building model error

I've created a building model in max, exported it into .obj and assigned textures in Model Editor.
Here it is:
Then, i sent files to my friend and he tried to put it inside the mod He got an error:
[ W AssetSystem ]: WARNING: Suppressing on-demand recompile of asset models/obelisk_bad_guys.vmdl
[ W AssetSystem ]: -> reason: Resource Compile Failed
[ W AssetSystem ]: -> This likely indicates a disparity between the assetsystem and resourcecompiler's views of the hard disk. Perhaps you forgot to add an extension to (sdk)assettypes.txt?
[ W ResourceSystem ]: File error loading resource header "models/obelisk_bad_guys.vmdl_c" (Error: ERROR_FILEOPEN)
So what shall i do to fix it?