[AccessD] Join expression not supported

I an getting a join expression not supported error from the following query. I am not seeing the problem. Thanks

SELECT dbo_DSS_CompletionMaster.PID, Right(ConfigMaster.PID,Len(ConfigMaster.PID)-4) AS WellName
FROM ConfigMaster, dbo_DSS_CompletionMaster
LEFT JOIN ConfigMaster ON Right([ConfigMaster].[PID],Len([ConfigMaster].[PID])-4))= dbo_DSS_CompletionMaster.Well_Number
WHERE (((ConfigMaster.PID) Like "PAT*") AND ((Right([ConfigMaster].[PID],Len([ConfigMaster].[PID])-4)) Not Like "*GAP") 
GROUP BY dbo_DSS_CompletionMaster.PID, Right(ConfigMaster.PID,Len(ConfigMaster.PID)-4);

Chester Kaup
Engineering Technician
Kinder Morgan CO2 Company, LLP
Office (432) 688-3797
FAX (432) 688-3799

 
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