Sum values from column based on criteria
I am trying to sum values from a reference sheet based on common criteria. However I am running into either "#INCORRECT ARGUMENT SET" or values that are not the exact sum as expected.
My idea is to SUM the values from the attached request sheet (column 12), into the corresponding rows (column SUM) in the attached tracker sheet based on the matchup with criteria in column 4 in request sheet.
I have tried SUM function with VLOOKUP, obviously gives different values than I expected, and I am still struggling to understand why (Probably it's my lack of understanding the behaviour of the functions).
I would appreciate any kind of help or a point in the right direction.