Not sure why you get this. Maybe a issue with the dev version of aircrack-ng your using. You might want to go to the aircrack-ng forums and ask darkaudix, he may can shed some light on this for you. Are you getting this with aircrack_0.91.lzm?? Or with the dev-1,0? or with another version??
aireplay-ng -0 1 -a [BSSID_AP] -c [MY_BSSID_CLIENT] wlan0 command instead.