Hi Nancy,<br> I think that the atom C1 in residue TRP 1 does not exist in rtp entry. In other words, atom C1 is not understood by the software. You should change the atom type in order to be understood. I have a question, how do you obtain the URL about trehalose. Because I want to some polyols from PDB. Can you tell me how to obtain the pdb files about orginic molecules? Thanks a lot!<br>Good luck!<br> <br>Fufeng Liu<br><br><br>