Adding dynamic columns to an ASP.NET Gridview

I'm having a problem dynamically adding columns to a GridView. I need to change the layout -- i.e. the included columns -- based on the value in a DropDownList. When the user changes the selection in this list, I need to remove all but the first column and dynamically add additional columns based on the selection.

I have only one column defined in my markup -- column 0, a template column, in which I declare a Select link and another application specific LinkButton. That column needs to always be there. When the ListBoxSelection is made, I remove all but the first column and then re-add the desired columns (in this sample, I've simplified it to always add a "Title" column). Here is a portion of the code:

RemoveVariableColumnsFromGrid();
BoundField b = new BoundField();
b.DataField = "Title";
this.gvPrimaryListView.Columns.Add(b);
this.gvPrimaryListView.DataBind();


private void RemoveVariableColumnsFromGrid() {
    int ColCount = this.gvPrimaryListView.Columns.Count;
    //Leave column 0 -- our select and view template column
    while (ColCount > 1) {
        this.gvPrimaryListView.Columns.RemoveAt(ColCount - 1);
        --ColCount;
    }
}

The first time this code runs through, I see both the static column and the dynamically added "Title" column. However, the next time a selection is made, the first column is generated empty (nothing in it). I see the title column, and I see the first column to its left -- but there's nothing generated within it. In the debugger, I can see that gvPrimaryListView does indeed still have two columns and the first one (index 0) is indeed a template column. In fact, the column even retains it's width which is set as 165px in the markup below (for debugging purposes).

Any ideas?

<asp:GridView ID="gvPrimaryListView" runat="server" Width="100%" AutoGenerateColumns="false"
    DataKeyNames="Document_ID" EnableViewState="true" DataSourceID="odsPrimaryDataSo