Problem: sd card not found

It's very strange, I can even use the SdCard in the menu to search for applications stored on sd card, but when I select to install an app on the market, it always comes to failure, because of sd card not found. Anyone knows why?

SDcard issue

Could you please tell us your device Brand and Model? There is a known issue for a limited number of devices in current SAM 3.x that was fixed in the next version 4.0 coming out soon.