hubFS: THE place for F#

I have a class in C# with a method with the following signature:

  protected virtual void OnChanged(string propertyName, object oldValue, object newValue) ...

In F#, I derive a class from that class (not directly, there are other classes in between) and implement a new member that calls this method:

    member public x.SetPropertyValueFS propertyName oldVal newVal = 
        x.OnChanged(propertyName, !oldVal, newVal)

When I try to compile, I get this error message: Error 5 A protected member is called or a base variable is being used. This is currently only allowed in the direct implementation of members since they could escape their object scope.

I can't find any reference to that error message anywhere. What does it mean? I've done tests with other calls into protected virtual methods and they work just fine.

Thanks
Oliver

This problem was solved with help from Brian McNamara, although the precise reason for the error message still remains unclear. If you're interested in the solution, please see my blog post here: http://www.sturmnet.org/blog/archives/2008/05/16/oddities-in-fc-interaction/