PDB file does not exist in I-TASSER run: I-TASSER2.1/PDB/3ja8A.pdb not exist

Hello I-TASSER Team,
I have a question concerning the program workings.
I have been running ThreaDom on many proteins, and in my runs I sometimes get errors like this one: I-TASSER2.1/PDB/3ja8A.pdb not exist
How can I solve this?
Thank you!