If the HP Toolbox says the that the refilled cartridge is empty (and I expect
it will) then you need to replace the chip.
Go to http://www.ink-refills.net/hp-2550-smartchip.html for one source of a
smartchip which will overcome the problem. Each cartridge has a different chip.
Tony
Are you saying that the chip is necessary? In a hp 2500 I refilled the black
cartridge and it worked even though I didn't change the chip. Of course the
ink level was grayed. Does the 2550 differ in this aspect?
See http://www.epinions.com/content_156222852740 according to this the printer
will stop printing when the chip says any of the toners or the drum has reached
"end of life". However I have seen other reports that say that the toner levels
are greyed out but the printer will still print. So you may be right and the
reviewer may be wrong, I don't know. But the cost of a chip may solve the
original poster's problem.
Tony