=SUM(((Sheet1!$B$2:$B$100=A6)+(Sheet1!$B$2:$B$100= A7)+(Sheet1!$B$2:$B$100=A8))*(Sheet1!$C$2:$C$100< ""))

array entered with Ctrl+Shift+Enter

or entered normally

=SUMPRODUCT((($B$2:$B$100=A6)+($B$2:$B$100=A7)+($B $2:$B$100=A8))*($C$2:$C$100<""))

Hope this helps
Rowan

Paul Sheppard wrote:
How do I use countif with multiple conditions

Column B has dates
Column C has Various data or Blank

I need to count the number of non blanks in column C if column A is one
of 3 dates

I have tried the array formula below, but am getting the wrong answer

{=SUM((Sheet1!$B$2:$B$100=A6)*(Sheet1!$B$2:$B$100= A7)*(Sheet1!$B$2:$B$100=A8)*(Sheet1!$C$2:$C$100<" "))}

A6, A7 and A8 are the cells witth the dates in