I have four Acomdata 250gb usb/firewire PushButton Backup drives. All four function well with my older 17" MacBookPro using tiger. None will mount on my late 2011 MacBookPro using 10.7. I've plugged them in, pushed the start switch, lights turn blue and......nothing. I've left them on for more than an hour hoping they'd be discovered but again, nothing. (Newer macBookPro has NO firewire so couldn't try that.) What's wrong?
MacBook Pro (15-inch Late 2011), Mac OS X (10.7.3), Purchased direct from Apple