#DIV/0! Errors when pulling from another workbook?

I need this to pull prefferably a blank or second prefference a zero in column D if columns A,B or C is empty while getting the value from a different workbook.

D=Formula
A-----------B----------C------------------D----------------------------
30 ----- 0.3571 ----0.3838---------- [=IF(COUNT(A2:C2)=0, "", (C2-B2)*1000000/A2)] (answer D= 890) works fine within the same sheet
A-----------B----------C------------------D----------------------------
Blank --- Blank --- Blank------------ [=IF(COUNT(A2:C2)=0,"",C2-B2)*(1000000)/A2] (answer D=Blank) works fine within the same sheet

Above works great when pulling the values from same sheet, but not from another workbook Example Below we get errors if the cells are blank in workbook 2 that were pulling from. If Values are filled in the cells then our formula works fine.

A-----------B----------C------------------D----------------------------
A=[='[Day 1.xlsx]Daily Water Testing'!$J$6] B=[='[Day 1.xlsx]Daily Water Testing'!$K$6] C=[='[Day 1.xlsx]Daily Water Testing'!$L$6] (answer D= #DIV/0!) not fine in this case

Thanks for you help, If I need to further clarify please let me know.

ps. the attachments are not the same columns nor workbook names to make it easier to understand starting off.

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