How do you beat level 39 on 40x escape

Only the A will light up by itself, when you press the middle button. You will have to "walk the light out" to the other letters by clicking the left or right button.
Press the middle button (turns on A) then use the left button to move the lighted letter to the E at the far left. Repeat the process to light up the other letters to either side, the s, c, e, p, finally the a to finish.