Crystal Reports Sum no matter what??????

Message

     Hi All,

I hope someone could explain the following to me:

I have a table with the Colums:
Date
Amount
InOut

I managed to summarise the amounts according to the boolean InOut (1 or 0).

Now I have come across the following error:
If the table has the following:
Date                 Amount        InOut   Location
01.01.2010        500                1          A
01.01.2010        500                1          A
01.01.2010        2000              0          A

The result always comes back due to the 2 x 500 as 1500 and not 1000.

Does anyone know why and how to fix this problem.

Info and Code Used:
Amount:Currency
Date:Date
InOut:Boolean
Location: String

#RTotal1
Summarize: Amount
Evaluate Using Formula:
InOut = True
Reset On change of field :Location

#RTotal0
Summarize: Amount
Evaluate Using Frmula:
InOut = False
Reset On change of field :Location

@SumT
CurrencyVar SHT;
CurrencyVat SHO :=0;
CurrencyVar SHI := 0;

SHO := {#Rtotal1}
SHI:= {#RTotal2}
SHT := SHO-SHI