How to correctly switch between Toggle Button with Yes/No?

Question

I'm struggling as to how to toggle switch between Toggle Buttons. What I want to happen is if Yes Button is pressed, then the No Button will be unchecked and vice versa. Right now, it is allowing the user to select both which I do not want to happen. Also, the Unchecked is used in the wrong format and it says it must only appear to the left hand side of += or -=, noTBU.Unchecked = true; & yesTBU.Unchecked = true; I'm not sure I understand this? I thought it returns true or false?

    // method to handle all Toggle Button tap events
    private void ToggleButton_Tap(object sender, System.Windows.Input.GestureEventArgs e)
    {
        if(yesTBU.IsPressed)
        {
            // add selected value to text
            // disable noTBU toggle
            //noTBU.IsChecked = false;
            yesTBU.IsChecked = true;
            noTBU.Unchecked = true;

            if(noTBU.IsPressed)
            {
                yesTBU.IsChecked = false;
            }
        }
        if(noTBU.IsPressed)
        {
            // add selected value to text
            // disable yesTBU toggle
            //yesTBU.IsChecked = false;
            noTBU.IsChecked = true;
            yesTBU.Unchecked = true;

            if(yesTBU.IsPressed)
            {
                noTBU.IsChecked = false;
            }
        }
        // makes dynamic changes immediately in UI
        if(yesTBU.IsChecked == false && noTBU.IsChecked == false)
        {
            // message box and text font change or Not Specified
            disabilityTBL.Text = "Are you disabled? *";
            disabilityTBL.Foreground = new SolidColorBrush(Colors.Red);
            disabilityTBL.FontWeight = FontWeights.Bold;
        }
        else
        {
            // set back to default layout
            this.disabilityTBL.ClearValue(TextBlock.ForegroundProperty);
            this.disabilityTBL.ClearValue(TextBlock.FontWeightProperty);
            this.disabilityTBL.Text = "Are you disabled?";
        }
    }

Answer 1

Unchecked is an event, not common property. += and -= are respectively notation to attach and detach event handler from event.

Instead of setting Unchecked = true; I think you want to set IsChecked = false; :

noTBU.IsChecked = false;
//instead of noTBU.Unchecked = true;

UPDATE :

If you use same event handler to handle Tap event of both ToggleButtons, you can get currently tapped button from sender parameter. So, how about this way :

private void ToggleButton_Tap(object sender, System.Windows.Input.GestureEventArgs e)
{
    //if currently tapped button is yesTBU
    if(sender == yesTBU)
    {
        //set noTBU to opposite value of yesTBU
        noTBU.IsChecked = !yesTBU.IsChecked;
    }
    //else if currently tapped button is noTBU
    else
    {
        //set yesTBU to opposite value of noTBU
        yesTBU.IsChecked = !noTBU.IsChecked;
    }
}