insulin cartridges

One would think this would be easy, but these insulin cartridges don't work as normal syringes. The needle that you insert seems to be a bit longer that needed and it's really difficult to get the air out. Does anyone have a useful tip for this?

Hello, I recently registered with a new GP and got an appointment to set up my new prescriptions so I could easily order my repeats. Unfortunately despite them typing them all from my old re-order form, and me quickly running my eye down the list on her screen, it turns out she added Lantus as...