converting WMA to AAC on itunes??

hey everyone!!

so i have a problem of converting WMA files to AAC files on itunes..i downloaded music from ruckus.com (my school is affliated with that site) and now when i try to bring that music to itunes…it says i'll automatically convert it…and when i select convert…it gives me this error message:

"One or more of the songs being added are the protected WMA format and could not be converted."

Is there anyway i could fix this problem…that would be soo great!

thank you!