This is because upgradeable international inventory is not shown on ITN. CO denominates these as R class and although it frequently bears a close relationship to the Z as shown on ITN, it is far from exact and occasionally has no relationship at all. The only way that I have found to try to track the availabilities at all is to check ITN a few times a day looking for movement in the Z's on flights that had been showing J9. This movement probably signifies that the yield management gang had been doing some realignment and possibly had released some seats into the R inventory. Then you must call immediately. Does it always work? Of course not, but it is something to sort of hang your hat on and works often enough so that it is worth doing and is really only useful if your dates are somewhat flexible.
I have edited this post to explain that the duplication and repetition of cigarman's post was due to having been called away from the computer in the middle of writing the post.

[This message has been edited by monitor (edited 05-31-2001).]