The BC safer switched lampholder is very handy as it has a built in safety feature meaning you cannot turn the lampholder on without a light bulb inserted.
There will be a red pin in between the 2 brass pins, this is the safety feature and the concept is that the light bulb will push that pin down to allow the push bar to slide across.
Below are some tips for if your push bar is not pushing over or just not lighting up.
Push Bar Not Moving Across - No Light Bulb installed
This is the more obvious solution however you may of realized by now that there MUST be a light bulb inserted for the push bar to push over.
Push Bar Not Moving Across - Light Bulb installed
If you have a light bulb installed then please carry out the following task.
Remove the light bulb and unplug the light from the mains, push down on top of the lampholder whilst tightening up the lock ring further.
This will push the skirt downwards and closer to the red pin meaning that when you put the light bulb back in it should push the red pin down further.
Push Bar Moving Across - Light Bulb installed - No Light Output
This one may be solved via the solution above.
Another thing to try and this does catch a lot of people out but a known working light bulb.
You can either take a known working light bulb from another lamp or take the light bulb you have and try it in a known working light fitting such as a centre ceiling light.