Does someone need to tell you to reformat it?Try fat16 and fat32.
...More information would be useful. If SD Formatter fails, download SdFat http://code.google.com/p/sdfatlib/downloads/list and run the SdInfo example and post the results.
Please enter a valid email to subscribe
We need to confirm your email address.
To complete the subscription, please click the link in the
email we just sent you.
Thank you for subscribing!
via Egeo 16