Why is there a part of one picture on the other, when I repeat the procedure?

[Strawberry]

% Cars
procedure cars
cls
for x: 1..3
grayCar1 := Pic.Scale (grayCar1, 1130, 800)
Pic.Draw (grayCar1, 0, 0, picMerge)
delay (transition)
grayCar2 := Pic.Scale (grayCar2, 1130, 800)
Pic.Draw (grayCar2, 0, 0, picMerge)
delay (transition)
grayCar3 := Pic.Scale (grayCar3, 1130, 800)
Pic.Draw (grayCar3, 0, 0, picMerge)
delay (transition)
grayCar2 := Pic.Scale (grayCar2, 1130, 800)
Pic.Draw (grayCar2, 0, 0, picMerge)
delay (transition)
grayCar1 := Pic.Scale (grayCar1, 1130, 800)
Pic.Draw (grayCar1, 0, 0, picMerge)
delay (transition)
orangeCar1 := Pic.Scale (orangeCar1, 1130, 800)
Pic.Draw (orangeCar1, 0, 0, picMerge)
delay (transition)
orangeCar2 := Pic.Scale (orangeCar2, 1130, 800)
Pic.Draw (orangeCar2, 0, 0, picMerge)
delay (transition)
orangeCar3 := Pic.Scale (orangeCar3, 1130, 800)
Pic.Draw (orangeCar3, 0, 0, picMerge)
delay (transition)
orangeCar2 := Pic.Scale (orangeCar2, 1130, 800)
Pic.Draw (orangeCar2, 0, 0, picMerge)
delay (transition)
orangeCar1 := Pic.Scale (orangeCar1, 1130, 800)
Pic.Draw (orangeCar1, 0, 0, picMerge)
delay (transition)
blueCar1 := Pic.Scale (blueCar1, 1130, 800)
Pic.Draw (blueCar1, 0, 0, picMerge)
delay (transition)
blueCar2 := Pic.Scale (blueCar2, 1130, 800)
Pic.Draw (blueCar2, 0, 0, picMerge)
delay (transition)
blueCar3 := Pic.Scale (blueCar3, 1130, 800)
Pic.Draw (blueCar3, 0, 0, picMerge)
delay (transition)
blueCar2 := Pic.Scale (blueCar2, 1130, 800)
Pic.Draw (blueCar2, 0, 0, picMerge)
delay (transition)
blueCar1 := Pic.Scale (blueCar1, 1130, 800)
Pic.Draw (blueCar1, 0, 0, picMerge)
delay (transition)
yellowCar1 := Pic.Scale (yellowCar1, 1130, 800)
Pic.Draw (yellowCar1, 0, 0, picMerge)
delay (transition)
yellowCar2 := Pic.Scale (yellowCar2, 1130, 800)
Pic.Draw (yellowCar2, 0, 0, picMerge)
delay (transition)
yellowCar3 := Pic.Scale (yellowCar3, 1130, 800)
Pic.Draw (yellowCar3, 0, 0, picMerge)
delay (transition)
yellowCar2 := Pic.Scale (yellowCar2, 1130, 800)
Pic.Draw (yellowCar2, 0, 0, picMerge)
delay (transition)
yellowCar1 := Pic.Scale (yellowCar1, 1130, 800)
Pic.Draw (yellowCar1, 0, 0, picMerge)
delay (transition)
end for
end cars

When I try to repeat the displaying of the pictures, a part of one of the pictures can be seen on another picture. Is there any way of making sure this doesnt happen?

Thank you!

[syntax_error]

use code tags, firstly. Secondly, its just matter of check your coordinates, and the check each image make sure there is enough space allocated for it and such.