My toner does not fit 2100 series

The lid on my 2100 series printer will not close, tried a compatible toner and an original HP C4096A toner, but it does not seem to fit, it goes in, but the lid wont close, the metal arm that lifts up on the toner when you put it in seems to obstruct the lid.

Am I going mad, taken the existing toner out and it looks like a totally different toner (bigger for a start) and the metal arm mentioned above stays in a totally different position on this toner which allows the lid to close?