SUMIF with dynamic criteria

[inky]

i'm hoping someone will be able to assist me with my SUMIF problem.

i've attached my sample worksheet and formula yet it's sadly incorrect.

what i'd like to do is, display the results as detailed in rows 13 to 16, being a summary of rows 2 to 10. i have a worksheet that contains 1600 lines of account codes, some repeated, and 250 columns. when an account is repeated in a column, it will only have one instance of data. yet where it is the second instance, a INDEX/MATCH simple stops at the first instance, so where it is 0, it's detailed as 0 yet actually has results (eg P2, P3, P5).

i believe a SUMIF is appropriate as it will add all the instances in a column (as suggested by the formula in C14), with only having to define a few ranges, yet the formula I have tried (B18) returns 0.