Every BizTalk developer knows that assemblies used by BizTalk must reside in the Global Assembly Cache and hence must be strong-named. As such, if you are using an assembly that reads a config section then in the BTSNTSvc.exe.config, you must specify the specific type of assembly in the GAC that will be used to read that section. Taking SubSonic for example. the config section should read like: <configSections> <section name="SubSonicService" type="SubSonic.SubSonicSect... SubSonic, Version=2.0.0.1, ......