Activity indicator does not show up

When I want to show Activity indicator it does not appear. Actually, the page is frozen and after that display the next page.

Here is my code:

`private async void TapGestureRecognizer_Tapped_1(object sender, EventArgs e)
{
try
{
if (txtNumOrden.Text != null && txtNumOrden.Text != "")
{
actLoading.IsRunning = true;

                EntregasModel entrega = new EntregasModel();
                entrega.shipperID = txtNumOrden.Text.Trim();
                entrega.token = this.cliente.token;
                await Navigation.PushAsync(new DescripcionEntregas(entrega));

                actLoading.IsRunning = false;
                txtNumOrden.Text = string.Empty;
            }
            else
            {
                await DisplayAlert("Error", "Favor de Introducir # de Orden", "cancel");
                txtNumOrden.Focus();
            }
        }
        catch (Exception ex)
        {

        }
    }`

Any ideas? I'll appreciate your help.

Thanks!