Digital BW, The Print

I just installed a new K7 cartridge in the Cyan position om ,y R 800
as it was out of ink.  My R800 now refuses to accept the cartridge and
complete the cleaning cycle.  The status monitor shows "incompatible
cartridge installed" and says the cartridges are not recognized.  This
is my second set of K7 carts and I did not have a problem installing
the first.  The strange thing is it now also shows the cart in the
yellow postion as out of ink.  It is at least half full and did not
show out of ink in the status monitor before I changed the cart in the
cyan position.  I have only replaced the cart in the cyan position.  I
have a new yellow position cartidge, but am reluctant to replace the
exisiting one as it does seem to have quite a bit of ink in it.  

I have cross posted this on the Piezography list, but there is not a
lot of action there.

Any ideas?

Steve