Nigge, i haven't had this problem before, but what i would suggest you to try is to:
1. Uninstall the mod tools
2 reinstall them, from UGX-MODS Confluence - ALL IN ONE link
3. Click the converter button in radiant before you do anything and leave it to finish
4. Use a script placer
That's it, i have never got that error before, so i am assuming you have downloaded the mod tools 1 by 1 by their versions, etc. Just try doing these what i said, and make sure to also save your map and all files that you need before uninstalling the mod tools. Except these, i don't know what else to say, have a nice day/night/evening etc whatever you want.