That is really strange. Maybe you should post in the BC thread about a possible bug, or someone there who knows the script could fix the issue for you. This should not be a big problem, and I am surprised you ran into an error at all. Check what version OBMM "thinks" it is. Right-click on the OBMM.exe file and check the version number.

The script contains no bugs, it works perfectly as it is.

 If VersionLessThan 0.9.3   Message "This mod must be installed by OBMM version 0.9.3 or later to prevent script errors."   FatalErrorEndIf

You need to have v0.9.3 or better of OBMM. So either you don't, or OBMM didn't install correctly. Reinstall OBMM.

The latest version does not give you spell. Instead, I think you can click on 'I'm missing mesh', especially if you install replacement 'WTF missing mesh' marker.