According to the feedback of some I-TASSER Suite users, we want to remind you that to run I-TASSER correctly, the users should download and install PSIPRED from http://bioinfadmin.cs.ucl.ac.uk/downloads/psipred/ by themselves. Then put executable files in the $libdir/bin/psipred/bin/ and put weight files in the $libdir/bin/psipred/data/.
Please read http://zhanglab.ccmb.med.umich.edu/I-TASSER/download/README.txt for more details.