I need a function something like =SUM(AB6)IF(F6:F6,"Complete") to show a number only if the work is complete (otherwise return a zero or blank)

I have achieved a week for a site visit based on the row date, in the column AB so I can then count how many sites were visited each week and also get averages etc. However in the adjacent column I want to return the same week number but only if the row information in column F6 says complete. I cannot seem to find anything to do this.

David