I have a fiat shower stall floor pan & I have a leak . I have removed the ceiling on first floor & the leak apears to be from above , plumbers putty didn't work , neo gasket missing & can't find replacement , any suggestions?

You have a rubber gasket missing on the bottom of the drain? If you mean the gasket under the lip you have installed it all wrong. The gasket goes UNDER the shower base. Is this the way you're configured? Did you unscrew the drain and run a ring of putty around the drain and reset it? Does the floor give a bit when you step into the shower? Let me know, Tom