For all the tracks, selecting "Part of a Compilation" - "Yes" solved this one for me (though it was not part of a compilation, it was the only way I could get it to cooperate).
This works, due to the way iTunes organizes compilations. The likely problem is that some of the files incorrectly have a compilation tag in the metadata and iTunes is looking for the same tag in the rest of the files and - not finding it - is placing the files in separate albums. Use a metadata editor to open up the files and clear the tag from the offending files and re-add them to your iTunes library and it should be all grouped under one album.
I tested this by adding a compilation tag to two files out of an album and importing to iTunes and did indeed get the files split into two separate albums. Removing the tag fixed the problem and iTunes imported correctly.