Xenons are working!! But 1 prob!!

[Mattsclio!]

Its really odd, one of my ballasts that ive got with my xenons will not go onto either of the shells? but a new one which i bought goes on perfectly on both shells? any ideas as to why my old ballast will not go on?

 

[Has]

Its probably from a different type of Xenon lamp unit.

Some were metal backed and others are complete plastic fitting.

 

[Mattsclio!]

ill jus get a new one which should fit