如何解决只能从脚本中调用类定义中具有[ScriptService]属性的Web服务

I attempt to use webservice return POCO class generated from entity data model as JSON when using Jquery AJAX call method in webservice. but I have problem with error "Only Web services with a [ScriptService] attribute on the class definition can be called from script", and getting stuck in it, I attempt to use webservice return POCO class g