Keep getting P0440 code. on 2001 Chevrolet Blazer

I keep getting the 440 code. had vapor lines replaced after smoke test. light came back 3 days later. had vent valve replaced, light still came back on 2 days later. i fill up, i turn gas cap like 3 times to make sure it sealed. Please help!

Asked by for the 2001 Chevrolet Blazer
you need another smoke test its probly in the fill neck