CF card not recognized on mac

[Olegphoto]

Suddenly my macpro and my Macbook pro don't recognize ( 10.6.7) all of my COMPACTFLASH card Sandisk. Says: The disk you inserted was not readable by the computer " initialize" Ignore or eject.
I reformat before on the camera and shot new images. could ot be the card reader? Any idea?
Thanks

 

[simsaladimbamba]

Does it show up in Disk Utility, and if so, what does DU say?