c# - Corner missing when drawing a square -

I have no idea why I can not find an ideal class at the time of drawing. I have this PointF of :

• [0] = {X = 1.80000067 Y = 101.8}
• [1] = {X = 1.80000067 Y = 103.6}
• [2] = {X = 101.8 Y = 103.6}
• [3] = {X = 101.8 Y = 101.8}

  And I'm using this code to attract:

    bitmap photo = new bitmap (1000, 1000); Graphics G = Graphics.frame image (photo); G.DrawPolygon (Pens.Black, pointsUpThere);   
   I am using  DrawPolygon ()  because they are not always the corner corners of a square. This can be a more complex shape.  
   Therefore, instead of a class in this example, I get this:  
   I do not get it, what does this problem mean?  
   Best regards!   
   
   
   OK, the x difference between points is 100 (hundred). Y is the difference 1.8.  
   Seems like a veeeeeeererery long rectangle.