Why do you have to completely seal the black, when refilling Canon ink cartridges?

Why is my Canon PIXMA iP2600 Printer not recognizing black ink cartridge after refilling?

• I got a Canon PIXMA iP2600 Printer a little while ago and this is the first time I've ran out of ink. I took it to get refilled and then when I put it back into the printer and when I went to print a document, a message popped up on the screen saying: "The following ink cartridge cannot be recognized. Black Printing cannnot be executed because the ink cartridge may not be installed properly or may not be compatible with this printer. Install the approproate ink cartridge." This message confused me because I had been using those exact-same two ink cartridges before I they ran out of ink and they printed fine. Now, for some reason, the printer will not recognize them. I would appreciate some help!

• Answer:

  It looks like the chip on the cartridge has either gone bad or could no longer be reset. The chip is what tells the printer that it is ok to print (i.e. there is ink available and that the cartridge is approved). Some chips will only be reset with available procedures a few times. Other times refillers are not succesful in resetting the chip or just give you another cartridge that is already refilled and could just happen to have a bad chip. You should probably return the cartridge and try to get one that will work based on the argument that refilling is not only related to ink but also to chip. Otherwise here is a web site that has a special page for your Pixma that contains all possible refill products: http://www.inkfilling.com/inkjet-refill-Canon--PIXMA--iP2600.html