Excel Sum function

Hi,

I am working on a mcaro that firstly separates rows into groups depending on certain criteria and then perform an autosum or sum formula for

A B C
1 Mary Sales 1000
2 Total
3 Joe Stores
4 Gerry Stores
5 Total

Sorry didn't finisg previous post!

I am working on a mcaro that firstly separates rows into groups depending on certain criteria and then perform an autosum or sum formula for values in 1 column. THe groups have random number of rows.

THe problem i have is with the sum function i can't seem to use the Index notation for the cells (1,4) etc or use a variable with the formula ="sum(R[x]C[y]:R[z]C[w)"
x y z w being the variables.

Any thoughts, am i missing something?
THanks.
odig.