"Unable to determine file system type" while recovering CF card

Hi,

I just found and loaded Recuva based on some suggestions in a photo forum.

I have a Lexar Pro Compact Flash Card (800x, 16Gb) that contains raw Canon files (.CR2). Recuva won't scan it. If I try to scan, I get the "Unable to determine file system" message; I've tried it with and without the "Scan for non-deleted files" option checked.

Windows won't open the card and indicates it needs formatting before use.

As background, I used the card in my Canon camera for several dozen photos. I downloaded some of them to Adobe Lightroom and left the card in a USB reader in the computer for an hour or so. When I returned, it appears the card had been corrupted. The notice to format shows up when the card is in the camera as well; I've tried it in two different Windows computers with a separate USB reader or the built-in reader. In each instance, Windows can't read it and indicates it needs formatting.

Any ideas would be appreciated,

Dan

Update -- I was able to recover the lost RAW files using a different utility called RescuePro. I'm not sure what that says about Recuva...

Dan