I got a complete solution to my problem. WD Support sent me this solution, but keep in mind that I had already updated my system from OS X Lion to X Yosemite.
We sincerely apologize for the inconvenience. We checked the screenshot provided and it seems like the hard drive hasn’t been reformatted for your Mac yet.
This device comes pre-formatted for PC. It requires to be reconfigured for your Mac. Our recommendation is to follow the steps provided on the link below so you can drag and drop files to the hard drive.
Formatting the drive will delete all the information that you have in it. This process is Data Destructive and cannot be undone. Once the process begins, all the Data on the drive will be lost!
- Plug your hard drive to your Mac
2. Once the drive appears on the desktop, double left-click on the Internal Mac drive. Choose Applications, then Utilities, and double-click on Disk Utility.
In the far left pane, choose the drive to be partitioned and formatted. Typically there are two listings for each drive, unless there is more than one partition on a particular drive. Choose the option that gives you the capacity of the drive. It is usually directly above the name of the drive.
There should be 5 options on the top of the Screen and you will need to click on Partition.
Under Partition Layout, click the drop-down box and click on 1 partition.
Click the Options button and choose GUID Partition Table. Then click on OK.
Back to the Top, you will see where it says Partition Information, Name Untitled One. You can rename the drive if you wish to.
Right under the name, it says Format. Make sure it says Mac OS Extended ( Journaled ).
Click on Apply on the Lower right Corner and then Partition on the New Window
If you have any further questions, please reply to this email and we will be happy to assist you further.
Western Digital Service and Support