I am trying to dock the variable domains of an antibody with its protein target in docking 2. The structure of the variable antibody domains are predicted from homology. I have a few different antibody and for all except one this works fine. One however gives the error message Prepack step failed. Check your input files. I have repredicted the structure of the antibody with various programs, but it keep on failing. What can the problem be? Is there any online program (in Rosie for instance) where I can check my input before I try to dock?