The seller tests the quality of each cartridge before it leaves the factory but on occasion cartridges featuring attached print heads, such as HP, Lexmark or Dell brands, do not print immediately. This happens because cartridges are kept flat or upside down before use and the ink settles away from the print head. For an easy fix, stand the cartridge upright for a few minutes and then place the print head down on a damp paper towel for three minutes. The ink will seep out of the print heads, priming them to print.