iTunes 11: album art tab is greyed out, so can't add image
I tried searching the web for this one, but no luck. In iTunes 11, when I open "Get Info" for an album iTunes cannot find the artwork for, the Artwork" tab is greyed out. Therefore, I cannot add album art manually like I have always done in iTunes. It still works for other tracks not related to this album which is made by a small institute for therapeutic reasons ("rhythmic entrainment" from the Strong Institute).
Now, I should say that I first tried to highlight about 3 albums by this artist to use the same album art on all of them. The album art window in the "Get Info" window is very small and in the lower right hand corner with at check box next to it. I dragged the jpg image into it, it displayed there, and the box became checked. But when I closed the window the the album did not have the art/image. And when I again open the "Get Info" window for multiple tracks or just one track for this album, there is no album art anywhere--plus, as I said, the tab is greyed out. WTF?!
Any ideas much appreciated!