Android 2.2 SDK - can't access SD when using phone as app testing device

I'm using my phone as t开发者_运维技巧he "emulator", e.g. running my app from Eclipse to the phone. I'm trying to access the SD card from within the app (create a folder, save a file), but the error I'm getting is almost as if the SD card isn't inserted (write permissions are granted inside manifest, too). What is wrong here?

Are you sure you don't have the SD card mounted through the USB connection? If it is mounted Android can't access it. Unmount it by swiping the top, then click on Unmount USB or similar verbiage.