Show "error" in cells Q34 and Q42 if C3,Q2 is left blank

I have a excel file where I need "error" in cells Q34 and Q42 is cells C3 and Q2 is left blank.


Currenty the formulae which I have in cell "Q34" is

=IF(P33=O33,SUM(Q11:Q31),"ERROR")

And the formulae in "Q42" is

=IF(P33=O33,SUM(Q35,Q34)-SUM(Q38:Q40),"ERROR")

Currently if Count of Range "B11:B31" does not match count of "P11:P31" the it shows error in cells "Q34" and "Q42"

Please help me anyone. thank You.

I have attached the sample workbook