cannot play iTunes songs purchased from old "AOL" account. Can play songs from Mac account

I have an extensive music collection I purchased on iTunes both with my original "AOL" email address and with my now "MAC" address. After i upgraded my iMac (2012) to Yosemite (10.10.3) i can no longer play songs that i purchased from AOL email address. I keep getting prompts to authorize computer... which i do and the computer recognizes my password... then when i attempt to play the song it starts the prompts cycle again. When i go into iTunes store i see two things happening: 1) some of the songs i purchased ((AOL purchases) will display i purchased them and have the button to play from there... but when i try to play nothing happens (tried this with mac purchased songs and i can play those). 2) also, some of the songs i purchased(AOL purchases) won't even show that i purchased them from the store. When i look into my history account of purchases i don't see many of the older purchases ( probably from about 2000 to 2006). I have been on the phone with support and even they seemed stumped. We tried sharing, changing old aol address but nothing seems to work!... Does anyone have any advice?:)