SSP tank tap fitting

After some help please, I have an SSP tank and I'm having truoble fitting a (Scootopia) fast flow tap. Starting with the nut on the tap and tightening onto the tank it runs off the tap thread before it tightens.
It looks to me like the thread on the tank might be too long, so I measured it and compared against a standard tank. Any thoughts?


It looks to me like the thread on the tank might be too long, so I measured it and compared against a standard tank. Any thoughts?

