Xamarin.forms Active indicator Progmatically Loading

namespace Ecla.ContentViews
{

public partial class NotiInout : ContentView
{

static ActivityIndicator activ_indi;
public NotiInout()
    {

        InitializeComponent();

        activ_indi = activityindi;
        activ_indi.IsVisible = true;
        activ_indi.IsRunning = true;
        Main_Grid.Children.Add(activ_indi);
        Grid.SetRow(activityindi, 1);

         Device.BeginInvokeOnMainThread(async () =>
            {
                await onpages();
                activ_indi.IsRunning = false;
                activ_indi.IsVisible = false;
              //  Main_Grid.Children.Remove(activ_indi);

            });
    }

    ActivityIndicator activityindi = new ActivityIndicator
    {

        //IsRunning = true,
        VerticalOptions = LayoutOptions.CenterAndExpand,
        HorizontalOptions = LayoutOptions.CenterAndExpand,
        WidthRequest = 25,
        HeightRequest = 25,
        Color = Color.DimGray,
        IsEnabled = true,
        IsVisible = true,
        IsRunning = true,
        BackgroundColor = Color.Transparent,
        Margin = new Thickness(0),
        Scale = 1,

    };

     private async void preweek_Clicked(System.Object sender, System.EventArgs e)
    {

        int _year = int.Parse(Pick_Year.SelectedItem.ToString());
        int _month = Pick_Month.SelectedIndex;

        Device.BeginInvokeOnMainThread(async () =>
        {
            activ_indi.IsVisible = true;
            activ_indi.IsRunning = true;
            await Pick_Binding(_year, _month);
            activ_indi.IsRunning = false;
            activ_indi.IsVisible = false;
        });
    }

}

}