Typed DataSet, GridView and Computed Column

[mirco]

Hi,
I have created a Typed DataSet. The DataTable is (distrimarket.D atiDT).
Then a GridView is populated. The last column is computed and it is the
difference between the previous two. I get this error: Unable to cast object
of type 'System.Data.Da taRow' to type 'DataTable1Row' .
Could you tell me what is wrong please ?
protected void GridView2_RowDa taBound(object sender, GridViewRowEven tArgs e)
{
System.Data.Dat aRowView drv;
drv = (System.Data.Da taRowView)e.Row .DataItem;
try{

if (e.Row.RowType == DataControlRowT ype.DataRow)
{
distrimarket.Da tiDTRow dati = (distrimarket.D atiDTRow)drv.Ro w;

if (!dati.IsQta_In viatoNull() && !dati.IsQTa_Res oNull())
{
sold += dati.Qta_Inviat o - dati.QTa_Reso;
e.Row.Cells[4].Text = sold.ToString() ;
}

}
}
catch (Exception ex)
{
string err;
err = "Descriptio n: " + ex.Message;
}
}