Retrieving selected data from DataGrid with IEnumerable<IDictionary> (Silverlight)

Question

I have an application that can dynamically load data into a DataGrid. What's needed is an object of IEnumerable<IDictionary>, and a List<Dictionary<string,object>> is supplied (each Dictionary in the list has exactly the same keys).

The data is loaded into the DataGrid and shown, but now I want to retrieve the data the user has clicked on. Using datagrid.SelectedItem, Silverlight complains it cannot evaluate the variable, not even when type-casted.

I tried keeping the List<Dictionary<string,object>> and retrieving the right data from it using datagrid.SelectedIndex, but this index changes when the DataGrid is sorted.

Does anyone know a solution to this problem?