sandwich plates

[Burning Pyro]

so i was hooking up my sandwich plate so i could throw in and oil temp gauge and a new oil pressure gauge. i had it finished and i went back under the car to make sure i had no leaks, and there was a leak.im not sure if you guys know much of the sandwich plates. i had it tight in all spots, it lloked to be leaking for the top, or mabe another input screw towards the top. any advise on to why this is or how to install this correctly, maybe i did something wrong? any help would be appreciated.