I wonder if you need to update the BIOS on the SAS card? This is from the firmware notes on the IBM site:
https://www-947.ibm.com/support/entry/myportal/docdisplay?lndocid=migr-5090848
Fixed an issue where external stroage will not be seen by the LSI2004 controller.
Also, make sure you don't have the slot turned off for that blade:
