Running totals when letters entered. IF statement

[Peta]

Hey if anyone can help it would be much appreciated! Urgent!!

I have a column of 6 cells (blank) which overtime can have either A/B, C, D,
E etc typed in them in any order. As soon as a letter is entered it should
link directly to a particular cell reference (in a different sheet).

It is for a cost management spreadsheet to track total costs of a
construction project over time. Time taken on the project is split in to four
stages and each completion stage is classed by A/B, C, D, E etc. These
letters need to be entered in to either of the four stages (time), and as
soon as a the letters are factored in, it needs to automatically sum the cost
information (eg from stage 'C' of the project), from another sheet (projected
costs) and add them in to the running total work sheet.
It also needs to ignore the blank cells that are yet to have letters entered.

Does this help? Thanks for looking


Matrix which info on completed stages is entered:
Phase 1 Phase 2A Phase 2

N D
C C E
D F
G





formula used in cost tracking sheet:
=SUMPRODUCT(IF--('Exec Sum'!$D$8:$D$13="A/B",'Uplifted NIA to GIA
ft2'!C57,IF('Exec Sum'!$D$8:$D$13="C",'Uplifted NIA to GIA ft2'!D57,IF('Exec
Sum'!$D$8:$D$13="D",'Uplifted NIA to GIA ft2'!E57,IF('Exec
Sum'!$D$8:$D$13="E",'Uplifted NIA to GIA ft2'!F57,IF('Exec
Sum'!$D$8:$D$13="F",'Uplifted NIA to GIA ft2'!G57,IF('Exec
Sum'!$D$8:$D$13="G",'Uplifted NIA to GIA ft2'!H57,IF('Exec
Sum'!$D$8:$D$13="H",'Uplifted NIA to GIA ft2'!I57,FALSE)))))))

Thanks all!