ASP.NET

Object reference not set to an instance of an object. 
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error: 


Line 93:             lblTotal.Text = [String].Format("{0:C2}", +_ordersBLL.Total.ToString())
Line 94:           
Line 95:             cbsPayment.Checked = _ordersBLL.sPayment
Line 96:             cbsFood.Checked = _ordersBLL.sFood
Line 97: 

string filename = f.Name;<br />
            Response.ContentType = "application/octet-stream";<br />
            Response.AddHeader("content-disposition", "attachment; filename = " + str);<br />
            Response.BinaryWrite(b);<br />
            Response.End();

Word.Application app = new Word.Application(); 
app.Visible=false; 
object template	= Missing.Value; 
object newTemplate =	Missing.Value; 
object documentType =	Missing.Value; 
object visible	= true; 
object optional	= Missing.Value; 
Word._Document doc =	app.Documents.Add(ref template, ref newTemplate, ref documentType, ref visible); 
doc.Words.First.InsertBefore (hdnVal.Value ); 
Word.ProofreadingErrors we =	doc.SpellingErrors; 
iErrorCount =	we.Count; doc.CheckSpelling( ref optional, ref optional, ref optional, ref optional, ref optional, ref optional, ref optional, ref optional, ref optional, ref optional, ref optional, ref optional); 
object first =	0; 
object last  =	doc.Characters.Count -1; 
string strTemp	= doc.Range(ref first, ref last).Text; 
doc.Close(ref saveChanges, ref originalFormat, ref routeDocument);
app.Quit(ref saveChanges, ref originalFormat, ref routeDocument);