aireplay help

[Gallo75]

Hello all,
First of all i'm new to backtrack, i've been using for like 1 week, so far i managed to dual boot installed XP and BT4 on my old sony laptop so that's an advance.

I've been playing around with both my linksys (flashed with dd-wrt) and my 2wire trying to break the wep keys, i've been doing it on both routers with no problems until i decided to hide the BSSID on the 2wire one, first 2 steps went well (airodump) but once i use aireplay i get this message:

No source MAC (-h) specified. Using the device MAC (00:1D:7E:9B:C6:42)
15:11:07  Waiting for beacon frame (BSSID: 00:24:56:A7:7F:C9) on channel 11
Please specify an ESSID (-e)

This is what i'm typing:

- aireplay-ng -1 0 -a (BSSID) wlan0...

I can see the BSSID when i use airodump but it only says "lenght 0" and i know that's mine cuz of the mac address but i've been searching on how to make it work if it's hidden with no luck.
BTW i'm using a linksys wireless USB adapter to do this with no issues (until now) i'm using the same USB adapter and BT4 to send this message everything works

anyone care to help?
thx all in advance, cheers