Have you rebooted the device? Have checked to see if your memory is full? Those are the two simplest possibilities.

If thats not it, you might try a factory reset but that would mean reinstalling all of your apps.

If you have a drive connected, it will use that as default for app storage, and sometimes will not let you install anything from the Dreamlink market (I had the exact same issue). I had to remove my usb drive, go into the Android settings and change the default storage device back to the internal storage, and reboot. That solved my issue, hope that helps