InputSlot option not behaving

[Dean Manners]

Hey all,
         With my supreme linux printing illiteracy Iv got an issue with printing to different paper trays.

The printer in question is a Brother MFC-8840D.

With "lpoptions -l" looking like:

BrMediaType/BrMediaType: *PLAIN THIN THICK THICKERPAPER2 BOND TRANSPARENCIES ENV ENVTHICK ENVTHIN
Resolution/Resolution: 300dpi *600dpi 1200dpi
TonerSaveMode/Toner Save: *Off On
Duplex/Duplex: DuplexTumble DuplexNoTumble *None
InputSlot/InputSlot: MANUAL MPTRAY TRAY1 TRAY2 *AUTO
PageSize/Media Size: Letter Legal Executive *A4 A5 A6 Env10 EnvMonarch EnvDL EnvC5 EnvISOB5 EnvISOB6
PageRegion/PageRegion: Letter Legal Executive A4 A5 A6 Env10 EnvMonarch EnvDL EnvC5 EnvISOB5 EnvISOB6
OptionTrays/Number of Input Trays: 1Trays *2Trays

Which, as expected, sends all prints to TRAY1.  However I seem to be unable to override the option with:

# lp -d MFC8840D -o InputSlot=TRAY2 test.pdf

The job just prints from TRAY1 as normal (yes theres paper in TRAY2 :)).

The only way I can print from TRAY2 is by modifying /etc/cups/ppd/MFC8840D.ppd

*DefaultInputSlot: AUTO
to
*DefaultInputSlot: TRAY2

Any ideas to where Im going wrong ?