[pups] Can't get a second DZQ11 to configure?!

Hi Guys, I've got a 11/73 with 2.11BSD. The hardware configuration is pretty typical - RQDX3, DEQNA, TK50, and one DZQ11. Everything runs fine, but now I need to install a second DZQ. The first DZQ has csr 160100 and vector 300, so according to my calculations the second should be at 160110 and vector 310. I set the switches, install the card, and then edit my system configuration to change NDZ to be 2, rebuild the kernel, reboot, and, .... Disappointment! When it gets up to init, it says: init: configure system dz 0 csr 160100 vector 300 attached ra 0 .... 172150 .... 154 tms 0 .... 174500 ... 260 ... etc ... nothing about the second DZQ. Everything else still works, including the original DZQ11, and it boots up just fine except that there's no sign of the second DZQ11. I figured I made a mistake building the kernel, so I double check my kernel configuration and yes, the file dz.h contains "#define NDZ 2". Just to be safe I delete all the objects from my machine's configuration directory and rebuild the entire kernel from sources (takes a couple of hours on a 11/73!). Still no joy - init only finds one DZ... And I'm sure I'm booting the new kernel because of the timestamp it prints out when you boot it. At this point I figured it's a hardware problem. Just to be sure, I pulled out both DZQs and swapped the switch settings on the two cards. This makes the original DZQ card now the "second" one at 160110/310 and the new card the "first" DZQ at 160100/300. Put it all back together and boot it up again - same results! Init finds the first DZ but not the second! Moreover, all the serial ports on the back that are now connected to dz0 (which is the card that used to be the second dz) still work! Of course, the ports on dz 1 (which is the card that used to work) are now dead. It seems like the two DZQ11 cards must be OK. Oh, and BTW, I even used the 11/73's console ODT to verify that all addresses from 17760100 to 17760117 respond. The only explanation I'm left with is a configuration problem. Is there something I don't know about rebuilding the 2.11bsd kernel? Is 160110/310 the wrong location for the second DZQ11? Thanks much, any suggestions are appreciated. Bob Armstrong