SUMIF - Need to add condition the applies an allocation percentage to shared costs

Hi all,

I'm new to the forum, but found many useful posts and am hoping someone may be able to assist.

I'm summing invoiced amounts based on their contract # and Req.# (summing from the "Invoices" tab), then need to apply an allocation percentage to reduce any shared cost invoices entered. The formula listed below works for cells that have shared costs, but does not work for cells that do not have allocation costs entered. I've searched and tried a few different options, but have come up empty.

=SUMIFS(Invoices!$H$5:$H$256,Invoices!$L$5:$L$256,"Req. 1",Invoices!$D$5:$D$256,$H24)-SUMIF(Invoices!$I$5:$I$256,"=S",Invoices!$H$5:$H$256)*SUM('S&U'!$Y$8:$AA$8)

My allocation is listed on the "S&U" tab and is broken out as follows: (the S&U formula above is summing WB,SB & P to get the allocation cost to equal 40%)
EB=40%
WB=30%
SB=20%
P=10%
S=Shared Costs

Original Cost = $3,000

Expected result from cell that has shared costs: $1,200

Result I'm getting from cells that do not have shared costs: -1,800

I was successful in getting a $0.00 return by adding "&=S" in the non-shared cost containing cells, but this means having to manually go in and change it to "=S" if/when a shared cost gets entered...

Hi,
Posts without an example sheet will get less responses, and even will remain without a solution.
It's less common that one will envision your file by only literal description, or will take the initiation to create it instead of you.

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Example of what I'm trying to do is attached

Any assistance would be much appreciated.

Thanks,
Cindy