Expanding a Mesh?

I'm trying to expand a Mesh with a function i found, but the result is totally weird!
Instead of actually making the mesh bigger it seems to stretch it really odd...
Here's the code i'm using:

Import sidesign.minib3d
Graphics3D 640,480,32

Local Cam:TCamera=createCamera()
PositionEntity Cam,0,0,-10

Local ent:TMesh = createCube()
updateNormals ent
MeshExpand(ent,3)

While Not KeyDown(KEY_ESCAPE)
UpdateWorld
RenderWorld
Flip
Wend

Function MeshExpand(MESH:TMesh,am#)
For k=1 To countSurfaces(MESH)
surf=getSurface(MESH,k)
For Index=0 To CountVertices(surf)-1
newx#=VertexX(surf,Index)+VertexNX(surf,Index)*am
newy#=VertexY(surf,Index)+VertexNY(surf,Index)*am
newz#=VertexZ(surf,Index)+VertexNZ(surf,Index)*am
VertexCoords surf,Index,newx,newy,newz
Next
Next
End Function

(I can't use ScaleMesh since it doesn't work the same way)