DataView question

Hello everyone, I am reading data from xmlstring into my dataset. Now when I try to create dataview on the default dataset table it gives me error. Here is my code : Dataset ds = new Dataset(); ds.ReadXml(xmlString); DataView dv = new DataView(ds.Tables[0]); dv.sort = “ ASC”; DataGrid1.DataSource = dv; DataGrid1.BindData(); I am getting runtime error - Table[0] not found. Please suggest. I don't know why DataView can't find table. Thank you C_sharpkid