cr, does the car actually start when you check this or just turning over because it will take a few secs to get oil throughout the engine. If you want to test for oil pressure find an oil outlet above the sump level and disconnect it crank the engine see what happens. The other option is to pull the valve cover and crank the engine make sure it is not just the cam oiler near the cap that is not working. It is messy but definitive.
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)