oil pressure Gauge no working

Ok i have a 69 barracuda i'm working on and i'm down to the last little items. Right now i cannot get the oil pressure gauge to work, i have changed the sender, checked the wiring, replaced the dash gauge (rally dash) and still nothing. The engine has oil pressure 35 PSI with a mechanical gauge i hooked up as a temporary check.

The Gas gauge, amp meter, water temp and dash lights all are now working. I did not think the volt limited would be an issue due to the fact the other gauges are working. Any ideas?