Using NCAA

I am trying to build peptide sequences containing NCAA to use for FlexPepDocking. After getting params file and rotlib file, when I am using fixbb to do mutation , I encounter with this error “COULD NOT FIND TORSION PARAMS FOR 30 30 6 31”  it shows there is no parameters for C-N-C-CA

I would really appreciate it if someone could let me know how I can build my peptide sequence containing NCAA without ignoring this torsions (i.e., importing 0      1 180.00 for related parameter in mm_torsion_params.txt)