Because may be it is dried inside. Check it out or get it exchanged.
Amanda, make sure it's a Canon compatible cartridge. You should be able to figure out through a distinct digital watermark on the same side as the trademark information. Once you ensure it's the proper cartridge, remove the protective tape that is used to cover the nozzle for safety purposes. After this, insert it into the printer cartridge socket, and this should probably do the trick.