Cannot access wifi with cracked pass

I have captured a WPA handshake from a nearby AP, and run it through oclhashcat to obtain the passphrase, however I'm unable to connect to it. I'm assuming I'm near enough as I was near enough to capture the handshake originally, and airodump-ng is giving a power level of around -60dBm. Adaptor is a Ralink 2870.
Everytime I try to authenticate, it just comes back with the password prompt again after a few seconds. Silly question but I am using the correct part of the hashcat ppt file as the password? I have something like ssid:bssid:???:password.

Any ideas? I'm sure the password hasn't been changed in the short time between me getting the handshake and cracking it, although I haven't recaptured yet.

mac address filter?
Sorry forgot to mention - that was my first thought although I spoofed my MAC to match a connected client and still couldn't get on.
Maybe the DHCP network range has been configured manually not to dish out any more IP's and that current attached devices have static addresses assigned to them.
Good point re DHCP. I might try and spoof the MAC of a genuine client and try to request a few specific popular IPs, ie /