Error Multiple columns cannot be converted to a scalar value

Hello,

I am attempting to gather a total occurance of an amount of tickets using a distinct values in a column which works great. 

But when I add filtering on which Year to sort my results on fails evertime with error "Multiple columns cannot be converted to a scalar value" (see DAX code below).

Is there a way to gather the total occurances using a distinct values in a column and then filter a Date or Year?

Thank you in advance.

CritSitTeamCount = 
            CALCULATE(
                DISTINCTCOUNT( 'CRITSITS'[Ticket ID] )
                    ,RIGHT('CRITSITS'[CritSit Event Type],6) = "Metric"
),

FILTER('CRITSITS', 'CRITSITS'[Year]) = 2020 )