Make sure the drive you are using has been formatted to work on the computer you are using.
This could happen when the drive comes formatted for Windows and you use it with a Mac.
Edit:
By Looking at your other post I see that the drive has been formatted.
Try uninstalling the software and downloading the one that came with the drive.
The software was erased when you formatted the unit.
You can restore the software from the link bellow:
