Let's say I have wired it correctly but still have a ground buzz.. what next?

[sears]

I'm wiring up a p-bass. I have wired these up a dozen times, dead quiet, never a problem. This time I can't get rid of that ground buzz, the sound that appears when you take your fingers off the strings.

When I turn the tone all the way down, the buzz disappears.

According to my multimeter, the connections are good. The bridge is wired up to ground.

I will continue to check my work. But for my own sanity, is it possible to have this problem if I have wired it correctly and what might be my next step in troubleshooting?

I'm using the Seymour Duncan diagram here:

http://www.sonfatherguitars.com/Schematics/P-Bass.GIF

[Rosewood]

Does it have the metal grounding plate under the pickups and are they grounded? Also if the grounds on the pots are depending on connection with foil only then I would run seperate ground wires between pots and ouput jack. I assume it has enough shielding right?