This is a bizarre problem. I'm trying to superimpose multiple conformations of the same protein using segments I expect not to change. LSQKAB bails with this error each time:

 *** RWBROOK error: point code unit    function
 ***                    1 -102    2    MMDB_F_Atom
 *** file   : 4ARC_rot.pdb
 *** reason : internal error #2 -- report to developer
 *** Execution stopped.

It also appears very likely that the superposition is wrong. I expect an RMSD for the superimposed atoms (main chain only) of less than 2 Å, yet the program reports that the RMSD is 7 Å.

Thanks to anyone for a diagnosis and prescription.

Charlie