Emissions leak

What is your question?

Hey have replaced the charcoal canister and a purse valve canister three times on this vehicle and it still comes up as a code throwing for the purge valve canister what else could this be I've tried blowing out all the lines I've tried everything I could think of . The car starts runs and drives just fine no issues but the engine light will not stay off

How long has your 2006 Chevrolet Uplander had this problem?

Over 6 months