I purchased 32 of these PSUs from a dealer on eBay and they are all REV1-REV4 and they all work fine for me using the dual BB. The only issue I saw was at the highest setting, I was only getting 12.30~.40v. This was resolved by tweaking the internal VR501 pot an 1/8th of a turn to the left. Other than that, I haven't had any issues with my older REV PSUs. Mine all end with an "A" though as J4bberwock has mentioned, so that could also be an issue.

Near where you plug in the power cord, you should see two glass domes there with AC written under one and DC written under the other. Do you see either one (I think AC should light up first) light up when you connect the power cable? If not I would say you have bad PSUs. Out of the 32 I tested, the one bad PSU I did have would power up (green light for AC & DC), but would shut down when placed under load. Both the green light for AC and DC would go out, and the volts would drop down dramatically on the LCD display.

@J4bberwock - Could I have adjusted the external pot on your dual BB to correct the issue of the PSUs only putting out 12.30v? I only ask as I adjusted the small pot on the bottom left of the breakout board, but didn't notice a change in volts on the LCD screen or my multi-meter (I was turning the external pot to the left). As mentioned above, I manually adjusted the pot on the inside as I was afraid to keep turning the external one of the BB.