I have an older HP printer (F2210) that still works great and I do not wish to replace it at this point. However, I am experiencing difficulty in purchasing quality cartridges. I usually purchase from my local Walmart. I have purchased 3 black cartridges within about 3 months that will not print. The first one was in a combination black/tri-color package. Color worked fine, black would not--gave me the E message. Recently I purchased the 2-pack black (#21) and neither cartridge would print--same E message. When I buy another cartridge or replace with an old cartridge, the E message goes away; therefore, I know it is not the printer. Since Walmart will not allow returns once they have been opened, I have spent over $60 on cartridges that do not work. What can I do?