C300 Contains Unsupported Media or Invalid Directory

I took some shots using my Canon C300 and transferred the contents with FCP7 but I am having issues on logging in and transferring the contents of the card. The error says:

Warning
"C300 A" contains unsupported media or has an invalid directory structure. Please choose a folder whose directory structure matches unsupported media.
The entire files works fine on VLC player. How can I fix this?
