SSRS running Total On Multiple Columns? - reporting-services

Question

I am creating one SSRS report in which I have one Tablix the data of that Tablix shown as below,
One Parameter --> Balance = 100
firstamt SecondAmt ThirdAmt RunningTotal
10 15 20 145
02 05 01 153
-30 -20 -03 100
So basically my RunningTotal fields value should be
RunningTotal = Balance + firstAmt+SecondAmt+thirdAmt and then update
Balance = Balance + firstAmt+SecondAmt+thirdAmt (Or RunningTotal)
and for then next row should use Balance= RunningTotal then calculate the next row runningtotal and so on. I tried using custom code, RunningValue but still got no luck.
Any help would be great, Thanks. And also my reporting server is 2008.
(In case of confusion feel free to comment.)
I tried following Custom code but it doesn't work
public dim finalRunningTotal as decimal = 0
public function CalculateRunningTotal (totalAmount as decimal, CheckAmount as decimal,pstAmount as decimal) as decimal
dim valueToReturn as decimal = finalRunningTotal + totalAmount + CheckAmount +pstAmount
finalRunningTotal = valueToReturn
return valueToReturn
end function

Answer 1

Here's one of doing it - use an expression like:
=RunningValue(Fields!FirstAmt.Value + Fields!SecondAmt.Value + Fields!ThirdAmt.Value
, Sum
, Nothing)
+ Parameters!Balance.Value
You may have to change Nothing to a different Scope depending on how your table is set up.
Works for me in a simple example:
Here the example is as above.
To simplify this you could add a Calculated Field to the Dataset like:
=Fields!FirstAmt.Value + Fields!SecondAmt.Value + Fields!ThirdAmt.Value
Which makes the RunningValue expression simpler:
=RunningValue(Fields!MyCalculatedField.Value
, Sum
, Nothing)
+ Parameters!Balance.Value