and the last,in code behind pageListForExportExcel.aspx.cs
use this :
protectedvoid Page_Load(object sender, EventArgs e)
Response.Clear();// this for clear any response
Response.Buffer = true; // and then set to Buffer is true
Response.ContentType = "application/vnd.ms-excel";// and this is for call type what you want to set File extention for save....you can export to pdf ,if you change value Response.ContentType
var process = new DataLayersCollections();//set here by name your BusinesLogic
var list = process.GetListFromDataTable(); //set here by name your functions
rep1.DataSource = list;
and the latter again .......
good luck ....
hope this help you.....