There is a difference in a PB sleeve and a hex head plug. Looking at the picture of the valve, it looks like you added the PB sleeve and then you added a plug. You just made that valve a closed center valve, and it will block the fluid through the valve, and with your FEL valve levers in neutral, the pump fluid is flowing out the relief vlave, and squealing, if it doesn't blow up anything.
Just remove the hex plug and use the PB in the normal way. The PB hose goes to the next valve.
Take a pic of the hyd block also.
If you look at Roy's PDF, it will show the valve with an open center hex plug in the PB port.
A PB sleeve blocks off the galleries and allows the pump flow to flow downstream.
If you add the closed center plug, it is a solid plug that extends into the valve and closes or blocks the pump fluid. The only fluid that flows out a Closed center valve is the cyl expended fluid.
If you unscrew the fitting and remove the hex plug take a pic from the side of the fitting and through the fitting, then we will know for sure. See if you can get a pic inside the PB port