Leaking fuel from petcock bolts?

I am just about finished getting my 1980 KZ440 on the road. I got it without starting, and a bunch of issues. I am just about done. Literally, the last little thing. I bought a new petcock because I knew mine was leaking. I wasn't sure if it was the petcock seal or what. It turns out that the fuel is leaking through the bolt holes?!?

How can I fix this issue? Or does this mean I have to get a new fuel tank?

Are there nylon washers on the bolts? and you're certain the leak is at the bolt heads & not the tank mating surface?

Make sure o-ring (# 13 in image below) and the nylon washers (# 17 in the image below) are in good condition. Ed

Thank you for the quick replies.

I realized my mistake, when I was looking online and stuff, then went outside to look at the work. I put the wrong bolts in. The bolts with the nylon washers were just sitting where they were. So I took the bolts out, put the ones with the nylon washers on, and fixed. I never even needed to replace the petcock. I just used the wrong bolts the hole time.
Silly mistakes.