formula not recognizing the null value.

[slmVimalraja]

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I am using if formula which refer the another cell value and shows the value in formula cell or shows null value.

Name box D10. formula followed below

=IF(A10>0,(D9+C10),"")

I am using another if formula which calculate the null value.

Name box D11. formula followed below.

=IF(A11>0,(D10+C11),"")

The results at name box D11 is [B]#value!.

as i understand that if formula not recognizing the null value. I advise the solve the issue.