Oil Pressure

This morning on climb out, my oil pressure gauge dropped to zero instantly. My indicator light didn't come on. I pulled the cowl and checked connections on the sender and the back of the guage( Vans Instrument Guage ) and everything seemed secure. Restarted and got an initial indication (about halfway into the yellow, but the needle was fluttery and then dropped.

Could someone advise me on how to trouble shoot this issue? I'm pretty sure I have oil pressure because the warning light which runs off another sensor is showing oil pressure.

Thanks

Got it solved - the gauge was bad.