MyPassport external portable drive will not mount

I have tried to mount this drive on my iMac and my Macbook Pro. It doesn’t show up anywhere. Yet, when I disconnect the drive, I get a message that I removed in improperly.

This started right after I upgraded the iMac to OSX Mavericks, and I thought that might be the cause, but the same thing happens on my laptop, which is still running version 10.7.3 (Lion, I think).

I have tried to download and install updates, but the updater cannot see it, either. Help, please.

Thank you! --Nancy

Product No.: WDBAAA5000ABL

Well, folks, I solved this myself. I just had to install a driver ( on my Mac and laptop. Thanks to those of you who took a look.