Can't Play--License expired

I have a SanDisk Sansa FC:  BH07O4SZIOO7943 or FCC ID:  UZB-ES20070309 (may have typed it wrong between “o” and “0”) and I have Windows Media Player.  I have synced all my listings into this device, and when I tried to play a song, it has this message “Can’t Play–license expired.”  I started all over and re-sync and the same message occurs.  Why is this happening and how can I prevent this from happening?

A “license expired” error can result if copy protection is enabled on your Windows Media Player, using wma format.   If you do have protected media, it can only be transferred using MTP mode.

If these are rips from your CD collection, be sure to turn off copy protection, under your rip settings.

The simplest solution to this situation is to format the device, and then retransfer your music.  Be sure to have backup copies of your music, since formatting erases all media from the device.  By formatting and retransferring, this will force the secure clock and ID information to synchronize.

The model information you gave us is diffficult to decipher.  Can you describe your model?