Ben constructs a perpendicular bisector of the line AB which is 6 cm long by using the Geometer’s Sketchpad. The following are the steps he uses.

 
Step 1: Draw a line segment which is 8 cm long.
Step 2: Highlight the line and select Construct.
Step 3: Highlight the line and the midpoint. Select Construct.
Step 4: Check the perpendicular bisector of AB to ensure it is correctly drawn.

Which step is not done correctly by Ben?