Is that an actual copy paste from your code??
If it is, then you might want to check the serviceUrl variable and change the url part of the string with the actual url of the webservices.
Besides, i don't see you adding the properties of the webmethod. Does the webmethod doens't require any kind of arguments???
Check your code with this little tutorial i posted yesterday $25.00 for someone to show me how to connect to a .NET web service