How to position a shape in a chart?

I am trying to position a shape in a chart in Excel through VBA.

I set the parameters of the position. The result is the shape in a slightly different position.

I have searched the Internet but I have not found a satisfying answer as to why this happens.

I use this code

Set shpRect = Chart1.Shapes.AddShape(msoShapeRectangle, 50, 75, 250, 175) 

It generates a rectangle not in the 50, 75 position but in the position 60, 80.