Your COUNTIFS
formula specifies an end date but no start date, if you want to count for a specific month and year (based on C1) you need another criterion to specify the start date using C1, i.e.
=COUNTIFS('SALES LEDGER'!A:A,F2,'SALES LEDGER'!C:C,"<"&EOMONTH('MONTH Sales by Sales Type'!$C$1,0)+1,'SALES LEDGER'!C:C,">="&'MONTH Sales by Sales Type'!$C$1)