How to save the OLAP Report (.xml) programmatically?

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        string connectionString = "Enter a valid connection string";
        DataManager = new OlapDataManager(connectionString);
        this.OlapClient1.OlapDataManager = DataManager;
        this.OlapClient1.DataBind();
    }
}
protected void Button1_Click(object sender, EventArgs e)
{
    this.OlapClient1.SaveReportSet("Sample.xml");
}

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
                If (Not IsPostBack) Then
                                Dim connectionString As String = "Enter a valid connection string"
                                DataManager = New OlapDataManager(connectionString)
                                Me.OlapClient1.OlapDataManager = DataManager
                                Me.OlapClient1.DataBind()
                End If
End Sub
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs)
                Me.OlapClient1.SaveReportSet("Sample.xml")
End Sub