Excel 2007 :: Calculate Total Value Depending On Certain Criteria

I use Windows Vista and Excel 2007.

So to cut to the chase :

On my spreadsheet, I have 6 main groups of columns, each one comprising 4 columns with their own automated calculations across the range.

Group 1: Cell H5, Cell I5, Cell J5, Cell K5
Group 2: Cell L5, Cell M5, Cell N5, Cell O5
Group 3: Cell P5, Cell Q5, Cell R5, Cell S5
Group 4: Cell T5, Cell U5, Cell V5, Cell W5
Group 5: Cell X5, Cell Y5, Cell Z5, Cell AA5
Group 6: Cell AB5, Cell AC5, Cell Ad5, Cell AE5

Then I have two columns following those: Col AG, Col AI

In each one of those two columns, I am trying to sum up a total value using The IF Function.

In Cell AG5 : the sum of the values of cells K5+O5+S5+W5+AA5+AE5,

ONLY IF the values of Cells H5, L5, P5, T5,X5, AB5 is equal to AG3 (which is a symbol (wingding 3 for capital P), this occurs 3 times out of 6, sometimes twice only, and at random, so I need the sum of 3 cells (or 2) out of 6, based on the above criteria.

Same in Cell AI5: sum of the values of cells K5+O5+S5+W5+AA5+AE5

ONLY IF the values of Cells H5, L5, P5, T5,X5, AB5 is equal to AI3 (which is a symbol (wingding 3 for capital L), this again occurs 3 times out of 6, sometimes twice and again at random, so again I need the sum of 3 cells (or 2) out of 6, based on the above criteria.

Using the formula: =IF(T5=AI3,(W5),0) , I retrieved the value of cell W5 into cell AI5; and when I tried the formula :

=IF(T5=AG3,(W5),0) , in cell AG5, it returned the value 0 which is correct again, as T5 was equal to AI3 but NOT to AG3.

But I cannot work out how to add all of the three values relating to each symbol, independently in each column, as they each occur randomly.

This is the way it looks in the spreadsheet:

Cell H5 Cell I5 Cell J5 Cell K5/ Cell L5 Cell M5 Cell N5 Cell O5/
Symbol (for P) Text Text Value /Symbol (for L) Text Text Value

And so on 4 more times across.

I could of course add it all manually for each line but I would rather have a formula to do it for me as all the other calculations are automated and/or conditionally formatted.