First, make sure that you have enough space on your device and the files you want to add are supported by the player. If there is enough space, I suggest you format the device because there seems to be a malware file that blocks the transfer. You should find the formatting steps in the player brochure, but basically you need to press X once and to use the >> and << keys to select the FORMAT option. If the problem is not solved, navigate to RCA Downloads page, select your device model and download and install the latest version of RCA Digital Voice Manager.