Gridview To XML with Custom Schema

GetData();
DataSet ds = new DataSet();
DataTable dtxml = ((DataView)GVHostDtl.DataSource).Table;
ds.Tables.Add(dtxml);
ds.WriteXml(Server.MapPath("~/" + xmlFileName));

i have question ..So i have Grid where the data are binding from SQL..And i will export/download file to .XML files..its success but the header table XML files are not same with "Schema" on Grid..ex= i have field 'Actual Duty On Time In' on grid but on exporting file .XML field header name changes to 'Actual_Duty_On_Time_In'

Data My Gridview

Data .XML