Just in case you aren't aware, the shielding paint needs to be connected to a ground in order to work properly. For the control cavity, you could run a bit over the ends on the top so that it touches the grounded control plate. For the pickup cavities, you are going to need to run some ground wires in - probably best connected to the paint via small screws that the wire can be wrapped around then screwed down - or else use a small washer under each screw.

You may have run, or tried to run paint down the connecting holes to join up the cavities - in which case check with a multimeter that you've got continuity. In theory, anything under 1 meg ohm should work, though the lower the resistance the better.