Getting button as return type from function

I have function which search a particular name button in grid by name and return button.

 public Button search_Button(TextBlock position, Grid grim)
        {
           try
            {
                var temp =position.Text;            //getting position of button
                object item = grim.FindName(temp);
                Button tbtn = (Button)item;
                return tbtn;      // return button
            }
            catch (NullReferenceException ex)
            {
            }
        }

but it is not compiling giving error "not all code path return a value. What is wrong with my function?