ML110 G7 can't see additional drive

Hi,

I purchased a HP LFF SATA 500Gig drive but after installing it into the drive bay (#2, original 250Gig in bay #1) it only sees the original in bay 1. How do I get BIOS to see the additional drive? I've looked at F9 etc at startup at the HP screen but there's nothing about drive setup.

Thanks,

Paul