Gridview To XML with Custom Schema

Question

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