Thank you Josh. Doh!... RTM. Installing a Drive Blank in the Front Bay When the drive blank is inserted properly the lights will come on on the front of the cage. I was not opening the handle on the drive blank... 
I have a six drive bay controlled by a PERC H700 If I put 4 Dell 1TB drives in and 2 Seagate 2TB drives works fine If I put 2 Seagate 2TB drives in and 4 WD Red 3TB drives only one of the 4 is recognized by the PERC H700 Adapter BIOS Configuration Utility It does not matter which slot I put the drive in, that one drive is picked up immediately. I have spent 6 hours looking at the drives  using disk -l and smartctl and gparted and I cannot see any differences I have formated (and cleared format) --the 1 drive works, 3 not I have created (and deleted partition) --the 1 drive works, 3 not Any suggestions much appreciated...
PERC H700 only recognizes three drives