caienf520 file system filter

I’m having a problem with a file system filter driver called caieng520. The
driver comes with CA Unicenter. Our driver presents virtual volume devices
to the system that provide volume snapshots. Our backup product, tries to
open a handle to the snap shot device after requesting a snap shot from our
driver. The create IRP is sent down to our volume, but a file system is
mounted and caienf520.sys attaches to the file system, so the create request
goes to the FS filter first. I used IRP tracker on our virtual volume
driver, FtDisk, Ntfs and caienf520.sys. The IRP goes to caienf520.sys who
fails it with STATUS_INSUFFICIENT_RESOURCES without first sending any IRP
down its stack. Our driver never sees a create IRP. If I pause in the
debugger right before the CreateHandle call on our virtual volume, assign
our virtual volume a drive letter and look at it in a command prompt, I can
then open a handle to it. Otherwise, no amount of retries or sleeps lets
our backup app get a handle to the volume.

First of all, is there a CA developer out there who knows what’s going on?
I can’t seem to get through CA support.

Has any one else run into this or anything like it before? It’s stange that
explorer and cmd can get a handle to the device, but I can’t. My driver
doesn’t get any IRPs as a result of my CreateFile call.