try using...
B=BUTTON()
IF B AND 1 THEN GOTO @MVUP
IF B AND 2 THEN GOTO @MVDWN
IF B AND 4 THEN GOTO @MVLFT
IF B AND 8 THEN GOTO @MVRIT
Instead of...
BOTTON=BOTTON
IF BOTTON AND 1 THEN GOTO @MVUP
IF BOTTON AND 2 THEN GOTO @MVDWN
IF BOTTON AND 4 THEN GOTO @MVLFT
IF BOTTON AND 8 THEN GOTO @MVRIT
It was all in the screen shot I posted.