Calling metod on aspx page from ascx control

[AlphaOne]

I have a aspx page default.aspx on this page is a panel control and I load ascx user controls in to the panel. Like this.

Public Sub loadpanel(ByVal filename As String)
        Session("page") = filename
        'If File.Exists(Request.MapPath(fileName)) Then
        Dim demo As System.Web.UI.Control = Page.LoadControl(filename)
        Panel1.Controls.Add(demo)
        'End If
        
        
    End Sub

That is all working, But! Now I need to call the sub loadpanel from the ascx page so I can load a new ascx usercontrol on a button click. Something like this
Code on the ascx page to call the sub on the default.aspx

    Protected Sub btnCancel_Click(ByVal sender As Object, ByVal e As 
Loadpanel(“top.ascx”) ‘ This sub is on the deafult.aspx page
    End Sub

This is not the correct syntacs so how do I do this??