How to specify group in RunningValue function in SQL Server Reporting Services?

Question

I have a data set with the following fields:

Serialnumber, Dateofpayment, Paymentamount, Sourcecode and Campaign.

My data has only two campaign types, BS12 and BS13.

I'm trying to plot a running total of the payment amount by Campaign. In the chart I have the following expression for the Y value:

=RunningValue(Fields!PAYMENTAMOUNT.Value, SUM, "Campaign")

However, I keep getting the error:

The Y expression for the chart 'Chart1' has a scope parameter that is not valid for RunningValue, RowNumber of Previous. The scope parameter must be set to a string constant that is equal to the name of a containing group within the Tablix 'Chart1'.

I've looked up multiple sources and I feel like I am doing the right thing, Campaign is clearly a field in my tablix and I have entered it as a string. Why is the error occurring? - Can someone help me?

Answer 1

It's complaining about the scope parameter: "Campaign". Rather than pass the column name to the function, you need to define a group (if there is not one already) on that column in your chart and pass the name of the group instead. An example here.