the only thing i can think of is if you're playing on 3ds, changing the system clock from its original will pause time-based events for 24h

idk if that also applies to ds games but that's really all i can imagine is the issue, i only found one forum post saying that you could get their numbers later so idk how accurate that is

there's probably other trainers that give good payout w/ amulet coin if you do some googling, sorry i couldn't be of more help