Hi there! My name is***** am a computer professional with over 15 years of experience with both Mac and Windows computers, phones, tablets, and printers. It would be my pleasure to assist you with this. Can you tell me please what version of OSX you have on your MAC? If you aren't sure, from the Apple menu, choose About This Mac. Your version of OS X appears directly below “OS X".
Also, when you used disk utility, did you partition it first, then try formatting? If not, I'll provide detailed instructions for preparing this drive to work with your MAC using Disk Utility. Please let me know. Thanks!