Using Select Excluded as URL Parameter

[#1]

I have no trouble getting fields selected through an AccessPoint URL using the syntax:

     &Select=Document\LB03,(XAV|153)

However, I would also like to do the same for excluding selections. This worked for a while:

     &Select=Document\LB08,(NOT+AA,UA)

But it has mysteriously stopped working (the exact same URL string that was working yesterday does not do the exclusions today). How can I do this?

Thanks,

Kyle Cooper