oil pressure sender???

check the connections at the gauge itself for signs of corrosion (or anything that may have lead to the gauge to go pop), and if you havent already get somebody to hook a manual gauge upto the motor to ensure you actually have pressure

 

The only possibility left is that the actual gauge is kaput?
If you have oil pressure, the sender is brand new (and not faulty) & all the connections are good. There is nothing else to go wrong - is there?

You need to get this fixed a.s.a.p. - in time for Autoitalia Scotland.