How to get new Data Source value in Data source dropdown in SQL Report Viewer Designer 2010

I am using Visual Studio 2010 with the ReportViewer Control 2010. I create a new report and choose New -> DataSet From the Data source: dropdown I see a list of namespaces and methods available for reporting against co开发者_如何学运维llections.

How do I get additional objects into this list as it seems to almost be semi random about what is shown in there?

Basically, I have referenced the DLL that contains my enumerable object as the source for reporting but it is not showing up in the Data source drop down.

I noticed the dataset does not appear if the source is exposed as a Property and not a method.

ie this fails to be a selectable data source.

public class FooData 
{
    public List<string> Data {get;set;}
}

but this will show up as a data source

public class FooData 
{
    public List<string> GetData();
}