Why does iTunes rarely find album artwork?

I know people say the album title and artist must be identical to what is in Itunes, however I see no difference in the title and artist I am often using. The punctuation even looks right.

I know Itunes has the album but when I select open the album in itunes I get the error message that -

"ITEM NOT AVAILABLE The item you’ve requested is not currently available in the U.S. store."

Which is false.