Can't download purchased album/songs

I downloaded the entire album of Dave Matthews Band Live at Fenway Park about 4-5 years ago on my ipod touch. i recently upgraded my wireless phone to an iphone and when i use my apple ID to download purchased content, only a few of the songs on this album are available for download. the rest of the songs have to be purchased. i've already purchased them though 😟 i dont want to pay again. somewhat intriguing: the name of the album on itunes has changed from aforesaid (Fenway Park) to DMB Live Trax, Vol. 6 between then and now. memory costs money so i never backed songs up because i can download previously purchased content. HELP!!