Hey Earl:
If you installed the JD Power Beyond kit for the backhoe, the 3Pt is cut out of the circuit when the backhoe is plugged in. The JD backhoe is mounted directly to the tractor and only lifted into position by the 3Pt.
If you have Power Beyond, it will have two hydraulic fittings on one side (tractor right on my 3320) and one on the other. For the 3Pt to work, the two fittings (one above the other) are connected by a hose with a quick disconnect fitting. Try this-- with the 3Pt connected, lift the backhoe up, and then lock the 3Pt with the Rate of Drop/Lock valve (below the seat weight adjustment knob) before hooking up the backhoe hydraulics.
Steve