C# - MessageBoxResult

[/code]               
MessageBoxResult result;
result = MessageBox.Show("Conflict: " + conflictName.ToString() + " is already in that period for 1 or more quarters.\nWould you like to replace it?", "Scheduling Conflict", MessageBoxButton.YesNo, MessageBoxImage.Warning);
if (result == MessageBoxResult.Yes)
[/code]

What is wrong with this? I'm using WPF, and it tells me "Object reference not set to an instance of an object."

>>4
I don't (the only non-free code I use are my BIOS and Wlan card firmware), and your argument is retarded.