Edited Unassigned: REngine.CreateInstance("RDotNet") Fails in F# [51]

following the example from the main page using F# (script), I did this:

#r "C:\TFS\Tff.RDotNetExample_Solution\packages\R.NET.1.5.3\lib\net40\RDotNet.dll"

open System.IO
open RDotNet

let environmentPath = System.Environment.GetEnvironmentVariable("PATH")
let binaryPath = @"C:\Program Files\R\R-3.0.1\bin\x64"
System.Environment.SetEnvironmentVariable("PATH",environmentPath+System.IO.Path.PathSeparator.ToString()+binaryPath)

let engine = RDotNet.REngine.CreateInstance("RDotNet")


and when I run it, I get:

System.ArgumentException: Value does not fall within the expected range.
at RDotNet.REngine.CreateInstance(String id, String dll)
at <StartupCode$FSI_0010>.$FSI_0010.main@() in C:\TFS\Tff.RDotNetExample_Solution\Tff.RDotNetExample\RDirectExample.fsx:line 12
Stopped due to error

Any ideas?