Did you add it as a reference?
I have noticed that 4.0 is glitchy and I have see and heard of so many errors using API, Wrappers, Assemblies, Etc. 
Dim g As Graphics = e.Graphics Dim rect As New Rectangle(50, 50, 100, 100) Dim BrushX As New LinearGradientBrush(rect, Color.Blue, Color.Indigo, LinearGradientMode.BackwardDiagonal) g.FillRectangle(BrushX, rect)
I used GDI only for my MPGH Twitter skin 


