My 'X' won't move up correctly! =[

'This code looks perfect, to me. Can anyone help describe why you can't move up correctly. It 'glitches every few lines, but moving down, right or left works perfectly..

' For now i'm ignoring the showcode SUB

' Thanks

DECLARE SUB getkey ()
DECLARE SUB showcode ()
CLS

DIM SHARED code$(1000), display, over, k$, movedown
display = 21
over = 50
movedown = 1




DO
k$ = INKEY$ ' storing the INPUT into the variable K


getkey ' this sub gets user input and outputs it correctly
LOOP

SUB getkey



SELECT CASE k$ ' menu selection for user input (K)

CASE CHR$(0) + CHR$(77) ' USER ENTERS RIGHT

IF over < 80 THEN

over = over + 1

LOCATE movedown, over: PRINT "X"

END IF


CASE CHR$(0) + CHR$(75) ' USER ENTERS LEFT

IF over > 9 THEN
over = over - 1


LOCATE movedown, over: PRINT "X"
END IF


CASE CHR$(0) + CHR$(80) ' USER ENTERS DOWN
IF movedown < 21 THEN
movedown = movedown + 1

LOCATE movedown, over: PRINT "X"
END IF


CASE CHR$(0) + CHR$(72) ' USER ENTERS UP
IF movedown > 3 THEN

movedown = movedown - 1

LOCATE movedown, over: PRINT "X" ' this is the part that is broken, i think


END IF

END SELECT





END SUB

SUB showcode ' JUST IGNORE, IDKK WHAT I WANT THIS TO DO, YET
position = 1

FOR A = display - 20 TO display
position = position + 1

IF A < 10 THEN LOCATE position, 1: PRINT A; " : "
IF A > 9 AND A < 100 THEN LOCATE position, 1: PRINT A; " : ";
IF A > 99 THEN LOCATE position, 1: PRINT position; " : ";

LOCATE position, 9: PRINT code$(A)



NEXT A


END SUB