I am trying to log the soap request and response messages of a service in C#. I have a ready made soap extension which does all this, however I am having trouble adding it t
Soap extension is only for using ASMX based service or client = Add web reference. Once you used Add service reference you are using WCF client API instead and you cannot use Soap extension. You must create message inspector instead.
If you need message logging only for debugging purpose you can use built in WCF message logging.