There is a bug in newer QT Versions which ignores not only the default InputSlot (standard Tray in PrinterSetting), but also the InputSlot the user may select. KDE apps always prints from Tray1. :(
I have tried to add Printers for each Tray, but it still prints from tray1.
What I am looking for is a workaround something like patching the print job to TrayX? Or any other Hack that works.
Note: when I print from commandline like "lpr -P PrinterName -o InputSlot=Tray2" or print from any GTK app it works as expected. Here is more information if you are interested in the bug:
http://old.nabble.com/openSuSE-11.4---Printing-bug-td31626744i20.html