Hi! I'm a Newbie (with a bad English...)

I'm trying to crack a test wi-fi network...
I set up a wi-fi network (ad hoc) witk a 5 char wep key.

I started BackTrack and typed this on my bash:

airmon-ng start NIC
airodump-nw --write capt.cap NIC and in the same time
airplay-ng -3 -e (essid) -b mac -h mac_pc NIC

now I have a problem because after 6 hours I have only 13000 IVs...

Can someone help me?