Runtime Exception :- Object Reference not set to an instance of an object

OK, so add a breakpoint to the 'result button' click event handler. Now step through your code until the error occurs

Compile time and Run time errors are very different things!

This it what happen when you try to use a reference that is not set to a valid instance of an object - ie. a null reference.

The following may be helpful when you wish to track down null references, and other exceptions, when running a program under a debugger. It's particularly useful when you are working with code written by others, and trying to figure things out :)

AppDomain has two interesting events:
AppDomain.FirstChanceException Event[^]
and
AppDomain.UnhandledException Event[^]

So you can write

static void FirstChanceHandler(object source, FirstChanceExceptionEventArgs e)
{
#if DEBUG
 if (System.Diagnostics.Debugger.IsAttached)
 {
  System.Diagnostics.Debugger.Break();
 }
#endif
}

And then assign the handler in your Main method

static void Main()
{
 AppDomain.CurrentDomain.FirstChanceException += FirstChanceHandler;
 // the rest of the Main method ...
}

Regards
Espen Harlinn

Use debugger as John already advised. For code project report, please use my directions from past Answers:

How do i make a loop that will stop when a scrollbar reaches the bottom[^]
When i run an application an exception is caught how to handle this?[^]

—SA

Hope you are using exception handlers like try, catch.. In that case, put the break points for the functions where you are getting the error and then debug ur application... You can't fix this issue, until and unless u follow debugging with break point/s...