Error 416

Hello Apple experts! I am new to Mac (leap of faith be we now have an iPod touch, iMac, iPad, iPhone... and growing!) so I don't know 100% my way around as I did with the other computer...

My son setup his own Apple ID account so he could use his iTunes gift card. He switched to his account on our iMac, created his account, went to the iTunes store and "bought" his music. His dollar amount has been deducted by the amount of the complete CD so I guess that much worked!

Now we get:

BUT: we can "see" his purchases in the iTunes store but we can't download them...so I click on the cloud to download the song and I get:

So...I'm stuck and would really like some help here!

Thanks

Duane

Nova Scotia

Canada

thediamonds@bellaliant.net