RAID 5 Issue on DELL poweredge 2800

I had a drive fail in my RAID 5 array at work. I replaced the drive with one that was slightly bigger, rebuilt it nd now the other 2 drives are now degraded in the array in the DELL openmanager web interface. What am I doing wrong. I took one of the degraded drives offine and forced a rebuld but to no avail.

help!