Any time you have problems with a port, be it digital or analog, always first look to see what else is connected to the port. In this case, RB6, T1OSO, PGC, and T1CKI all share AN5. Also on AN6 is RB7, PGD & T1OSI.

Without your code, we can't even begin to debug it. However, we can suggest you read the d/s to make sure that all of those functions are disabled. Also, it could be a hardware issue... if you are using ICSP, there may be interference with the ANx.

BTW, I don't see any reference to setting the TRIS properly... this is the most obvious issue.