My Passport Ultra not passing Complete Drive Test

Ordered a 1TB drive from Amazon, ran diagnostics and the complete drive test failed. Returned to Amazon, 2nd one arrived, complete drive test failed again. I’ve got an iMac desktop running Mountain Lion. Any ideas? Is this a glitch in the Drive Utilities program or could I have two potentially defective drives in a row? Thanks for any help!!

Hello, before running the test be sure to connect the Passport USB cable directly to the Mac, longer USB cables or USB hubs can cause power inconsistencies.