I made an asp.net app and need message box to notify user for something.
IF user enter only one or none search criteria, message should looks like "You should enter more than one criteria!". I tried with MessageBox.Show, but I get an error "Name 'MessageBox' is not declared". When I tried with msgbox, I get an error "It is invalid to show a modal dialog or form when the application is not running in UserInteractive mode. Specify the ServiceNotification or DefaultDesktopOnly style to display a notification from a service application." How can I use message box?