insert the records into excel useing C#

Hi All

i am doing insert the records into excel .

query is working fine, but records are  not inserting into Excel

 code is       like below

try
{
	string fileLocation = Server.MapPath("~/Upload/Test_Web.xlsx");
	System.Data.OleDb.OleDbConnection MyConnection;
	System.Data.OleDb.OleDbCommand myCommand = new System.Data.OleDb.OleDbCommand();
	strConn = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + fileLocation + ";Extended Properties=\"Excel 12.0 xml;HDR=Yes;\"";
	MyConnection = new System.Data.OleDb.OleDbConnection(strConn);
	if (MyConnection.State.ToString() == "Closed")
	{
		MyConnection.Open();
	}
	myCommand.Connection = MyConnection;
	string sql = "INSERT INTO [Sheet1$] ([username],[password]) VALUES('siddu', '4646')";
	// string sql =""Insert into[Sheet1$] (username, password) values('siddu', '344')";
	myCommand.CommandText = sql;
	myCommand.ExecuteNonQuery();
}
catch (Exception ex)
{
	// MessageBox.Show(ex.ToString());
	throw ex;
}

please suggest me 

thanks and regards

siddu