Argument null exception was unhandled in c#.net?

i've creating Crystal Report Viewer using c#.net with back end MySql. Key cannt be null error occured while executing. How do solve this problem.

Argument null exception was unhandled in c#.net?
The best fix is to ensure that the key being passed to MySql is not NULL but an actual key.





In addition you can put in an exception handler (try, throw, catch) to ensure that NULL keys are detected and properly rejected.





Without more detailed information I am not sure how much more I can tell you.