Roller Coaster Tycoon 2?

I put up garbage bins at the very start at the game however none of the guests are using them. I can tell because when I click on all my handymen it says that none of them have emptied out any garbage bins. My paths keep getting messier and messier, but I already have over 10 handymen! Why aren't my guests using the litter bins? I have a lot of them!