I have a 2016 Ford focus se. 4 cyl 2 2.0L FI FFV DOHC 122 CID. 100k miles. check engine light code is P1450 ( unable to bleed up fuel tank vacuum).1st I performed the ( finger test). A. Unplugged the wiring harness from the purge valve. B. Unplugged the vacuum line running from the purge valve to the gas tank. C. Started car, waited about 10 minutes, put my finger where the vacuum line would go, ( no suction). 2nd I bought a new charcoal canister and replaced it, ( I recall 2 or 3 times topping off the gas. ( didn't know that was a "no,no" with these topless gas systems. While I was replacing the canister, I took the wheel well off to see the condition of the lines running from the filler tank, I noticed no kinks,no punctures.Both times I cleared the codes with a ZURICH ZR11s code scanner.  The code keeps coming back on. What can I investigate now????