Hard drive stopped being recognized

I cant open my external Hard drive. Its a Lacie and its got its own power supply. It was working fine until I did a clean install of OS Lion. Now I can't accesses it. It appears in disk utility but instead of what I called it "AC Drive" I it is called disk2s2. Its greyed out and any attempt to repair or verify returns this message

Invalid Volume Header @ 0: unsupported format
Invalid Volume Header @ 319728958976: unsupported format
disk3s2 has CoreStorage features not supported by this fsck_cs version
Problems were found with the partition map which might prevent booting
Error: Storage system verify or repair failed.

Any advice?

Ive tried disk warrior. Since I heard it recommended but I can only select my drive in the hardware tab which tells me nothing other than the device is functioning normally.

Pretty fed up with this problem as Ive already spent all of my free time this week attempting to solve it.

Try using it on another computer just to see if it will show up also you might want to check the power supply I had a Lacie act up and it was several volts shy on output a new power supply fixed it then a year later the board went D.O.A. Like a lot of hard drives of late you may also need a firmware update to work with Lion.

Was the drive freshly formatted Mac OS Extended (Journalled) GUID set up after running Repair Disk prior to install?

How is this Lacie drive formatted? Is it Mac Extended (Journalized) like Harry asked or some Windows format?

Thanks for the replies. I don't have another mac I can try the hard drive on. It was formatted OS Extended before the install.

Well the problem is sorted. I resorted to using a data recovery tool. "Data Rescue" from Prosoft. Its not cheap ($99). So Im sorry if to anybody viewing this post hoping for another answer but thats It I hav'nt attempted to reformat the hard drive yet but I'm guessing it will be fine. Data Rescue is a great program me but it is expensive and the demo only offers the recovery of 1 file up to 10mb which is pretty useless.

Thanks for your replies
Good luck