Hum from Basslines APB active Pickup

[Birdman]

I recently installed a pair of active pickups in my bass. I'm using the set of basslines active pickups for a P/J setup. The 'P' pickup picks up a lot of 60 hz hum, but the 'J' pickup is clear as a bell. I've checked every connection and even reversed the pickups on the blend pot, but it's always the same. Any clues?