ASP.Net WebService/Jquery Post: Invalid Number of Parameters

A coworker ran into this one today as he was trying to call an old school web service using jQuery Ajax/Post. Keep throwing an exception/returning a 500 error. After some searching, both google and soul, it turns out that services that are expected to be used with scripts (Javascript or Jquery in this case) need the attribute ScriptService. Yeah, that’s it. The silly and cryptic message is really just an attribute needed on the code file above the service class. Go figure.