I just received a refurbished Dell PowerEdge R710. I have two 1 TB WD hard drives installed. I went into the raid config utility, and am getting this error: "configuration is not allowed error code unknown". I tried moving the HDDs from 0/1 to 2/3 slots. I also unplugged/plugged back in the raid card.
If using consumer desktop/laptop or NAS drives, they may simply be incompatible. What model are they? Where exactly do you see that message? Do you see any foreign flags on the PD MGMT screen?