WCF: Adding a behavior extension requires careful notation of the assembly path

When registering a behavior extension in the .config file the inialization might fail with the following error message:

An error occurred creating the configuration section handler for system.serviceModel/behaviors: Extension element 'myService' cannot be added to this element. Verify that the extension is registered in the extension collection at system.serviceModel/extensions/behaviorExtensions.Parameter name: element

This might be the case even if the syntax for the assembly/class is correct and even if the service host has access to the assembly.

The reason is that for this particular configuration, .NET requires you to:
1. Add the fully qualified name for the assembly
Example:
"MyAssembly.MyClass, MyAssembly, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null"
instead of:
"MyAssembly.MyClass, MyAssembly" - which normally does the job

2. Use the exact syntax for the assembly
You are not allowed to use any line break of white spaces at the wrong places.
Example:
"MyAssembly.MyClass, MyAssembly, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null"
instead of:
"MyAssembly.MyClass,MyAssembly,Version=1.0.0.0,Culture=neutral,PublicKeyToken=null" - note the missing white spaces between each attribute.

Microsoft has acknowledged this; yet not classified it as a bug:
https://connect.microsoft.com/wcf/feedback/ViewFeedback.aspx?FeedbackID=216431