SSRS Multiple Variable Level (Dynamic Grouping) Report with Parameters

I have an SSRS report where I have parameters for each level of the report (5 Levels Total).

Each Parameter Selection has five choices.

I'd have a stepped Report, and I wish for Level1 to display the value Fields!ColA.Value in the TextBox if ColA is selected in the Level1 Parameter.

If if ColB is selected for Level1, then the Textbox should display Fields!ColB.Value.

I have tried putting this expression in the Group Properties Expression, the Group Sort Expression and the Textbox of the row within the "Level1" Group, but without luck on converting variables to the actual report data:

Parameters!Level1.Value

or

Fields!@Level1&".Value"

Or

Fields!&Parameters!Level1.Value&".Value"

I'm using SSRS 2008 R2

John