Flashdrive is empty but "not empty"?

I think if you empty the files into the trash from the usb drive; and, while it is still connected, then Secure Empty the Trash, it should show all empty on the usb drive. Then eject the drive. Good luck.

Reformat it.

With the flash drive connected to your Mac did you empty the trash?

Steps for Reformatting a USB Flash Drive:

***
1) Connect the desired flash drive to your USB Port.

2) Open the Disk Utility. ("/Applications/Utilities/Disk Utility.app" by default.)

3) Select your flash drive from the list on the left-hand side of the application window. There should be two lines to choose from, the top stating the hardware name of the device, the bottom stating whatever you've named your flash drive. Select the top line.

4) Choose the "Erase" tab on the top right.

5) Choose the desired format and name for your flash drive. "MS-DOS (FAT32)" is the most compatible format (and the only available format that most versions of Windows will read), whereas any "Mac OS" format will be more efficient.

6) Set the security options to your preference for erasure of data (this shouldn't make a difference unless you value information-security).

7) Click the "Erase" button.

8) Confirm your desire to erase the flash drive.
***

The process is similar for any other re-writable media: DVD-RWs, External Hard Drives, and iPods.

is it possible to "empty trash" for only my flash drive leaving my normal trash intact? i find it really annoying having to copy the files i need on the drive onto the desktop; format the flashdrive; then move my "permanent" files back onto my flash drive.

I've had to do this before. Does anyone know what causes this?