Before installing your dell ink cartridges, Be sure to remove the red plastic clip from the bottom of each ink cartridge. When installing your dell ink cartridges, start by sliding the cartridge in at an angle as shown.
Then starting at the side closest to you, Slide your finger along the top of the cartridge towards the back of the printer until you hear a click. Do this for each color cartridge. Please note: If you press in the middle of the cartridge, It will be more difficult to install. For the black cartridge, instert it the same way.
Then use two fingers to slide along the top of the cartridge Until you hear it click. Heres a view of a cartridge not being snapped in correctly.
You will see if you press on the far side of the cartridge, It does not snap in. But if you slide your finger from the side closest to you To the side furthest from you, it will go into place. You can see the example again on this yellow cartridge.