I'm not sure why but when using this formula
=IF(U2<>"", MATCH(U2,R:R, 0), "")
to try and match a value that is typed into cell U2 with the same value that is obtained somewhere in column R with the formula
=IF(M2<>"", SUMIF(C:C, C2,M:M ), "")
doesn't work. It only matches the values if...