Unable to import WebService/Schema

I've created a web service (.Net 3.5), but when I try and add a web reference to it from another application I get the following error:

Custom tool error: Unable to impor开发者_如何学Got WebService/Schema. The parameter 'sectionGroupName' is invalid.

When I double-click it it takes me to the settings file.

How do I get around this?

Fix the sectionGroupName parameter.

Customizing SectionGroups and Sections in Web.config in C#