External Drive Not showing on my mac

[MRPHASE324]

I have a lacie firewire external hardrive. It's not showing on my mac when i plug in the firewire cable. When I put the usb cable in it shows right up. Now, when i connect the firewire cable to a friend's mac it shows right up. That's strange.. do you know what the problem is?

 

[Whitehill]

What kind of Mac do you have? What's the version of MacOSX? Do you know how the disk was formatted?

With the disk connected via firewire, and presumbably not mounted, run Disk Utility. Does the program see the disk? If yes, select it and click mount. Can you see it now?