Partial Class AfterSalesService_InvoiceNo
    Inherits System.Web.UI.Page

    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
        If TextBox1.Text Is Nothing Then
            Label1.Visible = True
            Label1.Text = "Invalid Invoice No.,Please Check The Invoice No. You Have Entered."
        Else
            Label1.Visible = True
            Label1.Text = "Invalid Invoice No.,Please Check The Invoice No. You Have Entered."
        End If
    End Sub
End Class