Crop Tool Bug

When i crop a pdf (print size 400cm x 132cm) and i select the crop area to the border of the "paper" i get a black line in the crop just on the border but it will print this black line.  (please look at the photo)

it looks that the crop tool 2 or 3 pixels outside the border of the working area can you fix this that the selection stay's within the working area. eyeballing this is not an option the flow chart is just to big

Thanks 

Marco