For loop problems?

Hello! Why lbProgressMsg.Text="Testing in progress..."; don't take effect? When i<=j, it display lbProgressMsg.Text="Testing is ended"; only? private void btnTest_Click(object sender, System.EventArgs e) { int j=100; for (int i=0; i<=j; i++) { progressBar1.Value=i; System.Threading.Thread.Sleep(25); lbProgressMsg.Text="Testing in progress..."; } lbProgressMsg.Text="Testing is ended"; }