While trying to apply force field, i got this error

[jalemkul]

Posted yesterday (please Google or search the forum first):

Fatal error atom C2 not found in buiding block 166MET while combining tdb and rtp

You need to interactively select terminal patching with the -ter option, otherwise an incorrect terminus is guessed (quirk of the CHARMM force field and a niche patch that is sometimes used).