Question : Formula and syntax for counting where 2 criteria must be met

I'm trying to get a count of occurences where 2 conditions are met.  I've tried using countif and sumproduct but neither is working.  I can generate the correct count for either condition on their own, but when I combine them I get a value error.  Data is on worksheet US.  My formula is:
=sumproduct((US!C2:C2438,US!C1073)*(US!D2:D2438,US!D1073))

Answer : Formula and syntax for counting where 2 criteria must be met

Try this..
=SUMPRODUCT((US!C2:C2438=US!C1073)*(US!D2:D2438=US!D1073))

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