Mp3 playerr problems?********?

my ipod got stolen so now i have an mp3. i used imesh to download free music, after i was done i dragged the downloaded music onto my mp3 file. it worked and i safely removedd the mp3 from my computer, when i tried playing the songs, it says "please activate" but only the songs i added from imesh? the songs i downloaded from previous times on the RCA website works... does anyone have any idea whats wrong!? its a RCA mp3.