Scrolling Text Error message

1

Hey guys, just getting to grips with scrolling text, could somebody please point me in the right direction for correcting this error message?

Thanks.

Error Scene=Scene 1, layer=Content Box, frame=49:Line 1: Statement must appear within on handler
scrollbox.scroll += 1;

Error Scene=Scene 1, layer=Content Box, frame=49:Line 1: Statement must appear within on handler
scrollbox.scroll -= 1;

Total ActionScript Errors: 2 Reported Errors: 2