I am trying to mutate a PDB file by using the following command (where I have set blank to the chain name as suggested in the related workshop tutorial).

mutate.pl -seq 1:A 2.pdb > 3.pdb

However I am getting the error,

premature end of library file, aa:-103079215

I have checked the PDB file for any missing residues but there are none. Currently I am trying on PDB file "3NPO" where I have tried convpdb.pl along with charmm22 to give output structure.
I appreciate any suggestions. Thanks in advance.