Darnit! UDA50 problem.

I got the 34, and I just located a UDA50 for it, known working. Cost me $30. I plugged it in, and connected the RA81. It's cabled like this: +----+ +-----+ |1134| | RA81| +----+ +----|+ 1 /-----3/ | | |----**** | | +2+ Cable 1 is the cable from the UDA50. Cable 2 is a normal SDI cable Cable 3 is attached to the RA81 **** is a 4-port SDI bulkhead plug. I have the UDA going in port 1, the patch going from port 1 to port 3, and the RA on port 3. I boot RT11SJ from a RX02 (Because I don't have a DU bootstrap) and tell it "boot du0:" The machine sits there. If I look, 2 led's come on the 2nd (terminator side) uda board, the first 2 closest to the PS. They strobe normally when the machine starts. They stay that way. If I halt the CPU, the BUS ERR light comes on. Did I foul up the cabling, or is the UDA or drive toast, or what?