Sorry for my mistake. I thought it is an Windows Application.

Yes in Web Application it is not calling the Page_Load event if you set the event wireup to false. For this create one Public Constructor with the Page name and associate the Page Load event there as

Code:
public _Default()
    {
        this.Load += new EventHandler(Page_Load);
    }
    protected void Page_Load(object sender, EventArgs e)
    {

    }