Make sure you have a reference to the Microsoft.Exchange.WebServices assembly, and a using Microsoft.Exchange.WebServices.Data; statement at the top of your code file. "These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

As suggested the OUTPUT is a waste of time (I'm not aware that you cannot send a value in via n output parameter, I never use them), you never consume them just pass information in. The error indicates that you are NOT passing in a BookID, so remove the OUTPUT and debug to parameter add value and make sure it has a value. Never underestimate the power of human stupidity RAH

Well, which statement occur that error? If you don't know where it is, debug it and get exactly error statement. And before rerun it, you have to check your sql express again. :)

Try debugging your code when this type of error occurs. This generally happens when you access a property or method of an object that itself is null. Apps - Color Analyzer | Arctic | XKCD | Sound Meter | Speed Dial

The cmd.ExecuteNonQuery should return the number of rows affected by the command on UPDATE statement in this case if you are getting this message "Your info modification failed " means that for some reason the SP is not updating or is passing null values in the parameters could ya please share the content of the SP that way we can give a more precise solution.