Nintendogs walkin problem !?

i have this problem. i wnted 2 do more than 3 contests a day so i went 2 settings and set the day baq one day, and made the time 1 minute till 12. then wen i try 2 walk my dog, it says i should let my dog rest! i tried 30 minutes later, and it still said tat! can ne1 tell me how 2 fix this? PLZ PLZ PLZ PLZ?!!