You probably didnt initialize the Snake:
Code:
Dim MagSnake as tSnake


With MagSnake
   'Set start values
   .PointCount = 20
   Redim .Point(.PointCount)

   .Name = "Mag-Net"
   .Score = magsnake.score+1

   'To move your snake
   .point(0).x = .point(0).x + directionx
   .point(0).y = .point(0).y + directiony

   'Move the points
   For n=0 to pointcount-2
      .point(n)= .point(n+1)
   Next
End With