You have not moved the shape by the correct amount.
When a shape is translated only its position changes.
The most accurate way to translate a shape is to mark where each of its corners will move to and then join them up. If the translation is 3 left and 2 down mark where 3 to the left and 2 down from each corner is. Work systematically and join each point to the one you did before.
Always check that the new shape is identical to the original.