aggregate function and GROUP BY Clause error : I am receiving an error below and I am not shure how I should rectify it. If I run the code below which is an inner select, it outputs an error stating:

> Column 'Staging.SabreAssignedCrew.UpdateID' is invalid in the select
> list because it is not contained in either an aggregate function or
> the GROUP BY clause.

    SELECT
    	StagingFlight
    ,	StagingCabinCrew
        FROM 
        (
        SELECT 
        	*
        ,	Airline + CAST(FlightNumber AS VARCHAR) + Suffix AS StagingFlight 
        ,	ROW_NUMBER() OVER(PARTITION BY Airline + CAST(FlightNumber AS VARCHAR) + Suffix  ORDER BY UpdateId DESC) AS StageRowNumber
        ,	SUM(CASE WHEN CREWTYPE = 'F' THEN 1 ELSE 0 END) AS StagingCabinCrew
        FROM Staging.SabreAssignedCrew) 
        sac

I tried adding a group by for sac.UpdateID later on in the query but still outputs the same error:
