Help! Epiphone G-400 SG Deluxe Wiring Problem

[no_quarter]

Okay, I'm at my rope's end with this guitar and I figured before I take it in to someone, I'd see if anyone's experienced the same problem.... I own an Epiphone G-400 Deluxe guitar that I purchased from someone. The pots were replaced with 500K Alphas and the pickups were swapped with Seymour Duncan Alnico Pros. The bridge pickup sounded awfully weak to me, so I put a Bill Lawrence L-500XL in its place. I still had a weak sound. I assumed it might just be the pots, so I recently ordered a set of CTS 500K pots and some .022mf orange drop capacitors. Referring to the Seymour Duncan website, I pulled the old harness and rewired it according to their diagram. The neck is wired with the green and bare leads soldered to the pot, the red and white leads soldered together, and the black to the left terminal on the pot. According to the diagram that came with my pickup, I soldered the green and white leads together, the black and bare to the pot, and the red to the left terminal. I checked my joints, sprayed them down with contact cleaner, and plugged in. Much to my dismay, the sound is very weak. To see if I was going crazy, I plugged in my epi Les Paul Standard (I've put new pickups in this one), and it sounded fine. Has anyone ever had this happen with a guitar? Any info that can be provided would be greatly appreciated.