XSan volumes don’t mount

I've got 4 XServe RAIDs and 5 XServes connected with QLogic 5200 fiber channel switches. Set up 2 volumes with XSan. The XServes mount the volumes inconsistently and one of them won't mount any volumes at all. Frequently after a reboot of an XServe, the XSan volumes do not appear on the desktop. I have to either restart again, or power cycle, and hope that this time they'll mount and they usually do. But on one of the XServes nothing I've done makes the volumes mount. In XSan Admin if I click the SAN, "Setup," and "Computers" I see the XServe computer, can authenticate to it and put in a software license number that is reported valid. If I click a volume name and "Clients", the computer appears in the list with "No Access" and "Not Mounted." Click on the either of the "Mount" buttons and status changes briefly to "Mounting" then reverts to "Not Mounted." On the system that won't work I've wiped the hard drive, reinstalled Mac OSX Server 10.4 from scratch, reinstalled XSan 1.4, done all updates, and even replaced the fiber channel card and cables. Nothing helps. On the QLogic switch, the port that connects to this system lights up with a green link light, just like the working ones. In SAN Surfer the port properties of this system are identical with other working systems. I/O Stream Guard is Enabled, Device Scan is Disabled. And I've tried using a different port and that system still won't mount the volumes. If I open the Transaction Log in XSan Admin and capture during clicking "Mount" I see only one difference. For the systems that work, the status number is "0" while the one that doesn't work has "100007": status 100007 type Any ideas on what's wrong here?