ArgumentNull exception in asp.net web application - asp.net

Question

I have developed an asp.net application in which input will be given through an excel sheet.
This application is working fine in a system with WINDOWS XP and MS office 2008.
If i try to run the same application in a system with WINDOWS 7 and MS office 2010 i am getting a Argument Null Exception.
Code:
foreach (var dr in data)
{
LHSupdate = new LHSUpdate();
if (!string.IsNullOrEmpty(Convert.ToString(dr["Associate Id"])))
{
AssociateID = Convert.ToString(dr["Associate Id"]);
}
LHSupdate.AssciateID = AssociateID;
if (!string.IsNullOrEmpty(Convert.ToString(dr["Associate Name"])))
{
AssociateName = Convert.ToString(dr["Associate Name"]);
}
LHSupdate.Name = AssociateName;
var designation = dsData.Tables["LHS"].AsEnumerable().Where(r => Convert.ToString(r["Associate Id"]).Trim() == LHSupdate.AssciateID.Trim());
if (designation != null)
{
foreach (var de in designation)
{
LHSupdate.Designation = Convert.ToString(de["Level"]);
}
}
else
{
LHSupdate.Designation = "";
}
LHSupdate.CourseName = Convert.ToString(dr["Trainings "]);
LHSupdate.CourseStatus = Convert.ToString(dr["Training Status"]);
LHSupdate.Score = Convert.ToString(dr["Credits"]);
LHSupdate.LearningMode = Convert.ToString(dr["Venue"]);
LHSupdate.StartDate = Convert.ToString(dr["Start Date"]);
LHSupdate.EndDate = Convert.ToString(dr["End Date"]);
lstLHS.Add(LHSupdate);
}
I am getting error in the line:
var designation = dsData.Tables["LHS"].AsEnumerable().Where(r => Convert.ToString(r["Associate Id"]).Trim() == LHSupdate.AssciateID.Trim());
Code:
private DataSet Getdata()
{
string connectionString = "";
string getExcelSheetName = string.Empty;
if (fuLHSEntry.HasFile)
{
string fileName = Path.GetFileName(fuLHSEntry.PostedFile.FileName);
string fileExtension = Path.GetExtension(fuLHSEntry.PostedFile.FileName);
string fileLocation = Server.MapPath("~/App_Data/" + fileName);
fuLHSEntry.SaveAs(fileLocation);
if (fileExtension == ".xls")
{
connectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + fileLocation + #";Extended Properties=" + Convert.ToChar(34).ToString() + #"Excel 8.0;Imex=1;HDR=Yes;" + Convert.ToChar(34).ToString();
}
else if (fileExtension == ".xlsx" || fileExtension == ".xlsm")
{
connectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + fileLocation + #";Extended Properties=" + Convert.ToChar(34).ToString() + #"Excel 12.0;IMEX=2;HDR=Yes;" + Convert.ToChar(34).ToString();
}
OleDbConnection con = new OleDbConnection(connectionString);
OleDbCommand cmd = new OleDbCommand();
cmd.CommandType = System.Data.CommandType.Text;
cmd.Connection = con;
OleDbDataAdapter dAdapter = new OleDbDataAdapter(cmd);
DataTable dtExcelRecords = new DataTable();
con.Open();
DataTable dtExcelSheetName = con.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
int count = 0;
foreach (DataRow dr in dtExcelSheetName.Rows)
{
getExcelSheetName = GetSheetName(dr);
if (!string.IsNullOrEmpty(getExcelSheetName))
{
cmd.CommandText = "SELECT * FROM [" + getExcelSheetName + "]";
dAdapter.SelectCommand = cmd;
if (getExcelSheetName.ToUpper().Contains("LEARNING"))
{
getExcelSheetName = "LEARNING";
}
else
{
getExcelSheetName = "LHS";
}
dAdapter.Fill(dsData, getExcelSheetName);
count++;
if (count == 2)
{
break;
}
}
}
con.Close();
}
return dsData;
}
Please help me in resolving this issue.
Thanks,
Raji

Answer 1

From your code it appears that the table can have two possible names.
Either give it always the same name that you're using later when reading:
dAdapter.Fill(dsData, "LHS");
Or you can take the table by index ignoring its name altogether:
var designation = dsData.Tables[0].AsEnumerable().Where(r => Convert.ToString(r["Associate Id"]).Trim() == LHSupdate.AssciateID.Trim());