RhinoCommon Mesh.Weld Error

Hi,

I have tried to use Mesh.weld member in Grasshopper (version 0.8.0050) on Rhino 4 SR 9
I think I did everything the right way (see code below), but I am getting this error :

1. error: Unable to find an entry point named 'RHC_RhinoWeldMesh' in DLL 'rhcommon_c'. (line: 0)

Is this Method not implemented yet ?
Any thougts ?

Many thanks,
Philipp

Code which produces error :

Dim testPt As New Point3D(0, 0, 0)
Dim testPt1 As New Point3D(1, 0, 0)
Dim testPt2 As New Point3D(0, 1, 0)
Dim testPt3 As New Point3D(1, 1, 0)

Dim test As New Mesh 

test.Vertices.Add(testPt) 

test.Vertices.Add(testPt1) 

test.Vertices.Add(testPt2) 

test.Vertices.Add(testPt3) 

test.Faces.AddFace(0, 1, 2) 

test.Faces.AddFace(1, 2, 3)  

test.Normals.ComputeNormals 

test.Compact  

Dim deg As New Double deg = 5 

Dim rad As Double = Rhino.RhinoMath.ToRadians(deg)  

test.Weld(rad)