NullReferenceException was unhandled
===

Have looked through extensive information online and have not found anything to fix this.  I'm very new to this, so apologies if this is so basic for you.  You're helping me learn :)

The application runs fine - BUT if the user selects NOTHING from the listboxes and instead just hits the 'Do We Match' button - that crashes the program. I need it to throw up an error requesting that they click a starsign in each list (official error is 'Null Reference Exception is unhandled).

Code for that part so far:

            // Method for starsign combinations
        public void Combinations()
        {

            ListBoxItem lbi = (ListBoxItem)yourListBox.SelectedItem;
            string yourListBoxValue = (string)lbi.Content;

            ListBoxItem lbi2 = (ListBoxItem)partnerListBox.SelectedItem;
            string partnerListBoxValue = (string)lbi2.Content;



            string listBoxValuesCombined = yourListBoxValue + partnerListBoxValue;

            if ((listBoxValuesCombined == "Aries" + "Aries") || (listBoxValuesCombined == "Aries" + "Aries"))
                resultTextBlock.Text = "On Fire - this is a hot combination!";



I hope someone can help, thank you.



