Calling F # functions from C # and getting null reference exceptions

I am using Visual Studio 2008 with Oct 2009 FTP CTP installed.

I am trying to call some F # code from my C # program. Most of the F # function types seem to work, but some are not initialized in F # and throw NullReferenceExceptions. The ones that do this are closures and partially usable functions, i.e. things that appear in C # as FastFunc <> types.

Is there something I am doing wrong or am I forgetting, or is this possibly a bug with F # or .NET?

the code below is meant to demonstrate the problem. I am not really trying to use this code in a real application. also, within F #, everything works correctly. this is an F # -to-C # problem

F #:

namespace FS      
module FunctionTypes =

    //these all work in c# as expected
    let Value = "value"

    let OneParam (str:string) = str

    let TwoParam (str:string) (str2:string) = str + " " + str2

    let Lambda =
        fun () -> "lambda"  


    //these functions are null references in C#
    // they do work as expected in F# interactive mode
    let PartialApplication = TwoParam "what up"

    let Closure = 
        let o = new System.Object()
        fun (i:int) -> o.ToString() + i.ToString()

    let ClosureWrapper (i:int) =
        Closure i  

      

        
        
        
      

    

C # (F # project and FSharp.Core links)

 //these work as expected:
        var oneParam = FS.FunctionTypes.OneParam("hey");
        var twoParam = FS.FunctionTypes.TwoParam("yeah", "you");
        var lambdaFunction = FS.FunctionTypes.Lambda();
        var value = FS.FunctionTypes.Value;
        //  in the May09 CTP, Value returned null, 
        //      so it must have been fixed in Oct09 CTP



 //these do not work--each throws a NullReferenceException.
        var partial = FS.FunctionTypes.PartialApplication.Invoke("hello");
        var closure = FS.FunctionTypes.Closure.Invoke(1);
        var closureWrapper = FS.FunctionTypes.ClosureWrapper(1);

 //  FS.FunctionTypes.Closure itself is null, 
 //  so is FS.FunctionTypes.PartialAppliction.
 //  FS.FunctionTypes.ClosureWrapper is a regular function, 
 //    but it calls Closure, which is null