As the OP finally found out, it was not a matter of using the wrong signal pair. As they said the probe was unable to read the device ID, it was just not (at this point) trying to debug anything. It failed at the identification step, which is a common first step for programming and debugging. Failing to read the device ID, if the probe works fine, is usually a hardware problem on the PIC's side.
Never had this issue with a bad connection to the VCAP capacitor, but had this with a bad connection to AVDD.