It's been a while, but I'm still here

It seems fakeraid is detected on sdc and sdd, ut not on sda and sdb. All 4 drives are part of the same software RAID-5 provided by the NAS-XSR. The only real difference I see is that both the sdc and sdd are RAID Edition verions of Western Digital 250GB SATA drives..... The other two are regular 250GB drives. Could this be the cause?