Trouble with an iPad

[Joshua Smith]

I've managed to get my MacBook Pro connected to my linux server running hostapd.  However, I cannot connect from an iPad.  I get the unhelpful message "Unable to join the network".

If I enable WPA-2, the iPad prompts for a password, and then gives the same message.

Since there is no way to diagnose the problem on the iPad side, I was hoping that someone on this list might be able to identify the issue by looking at my hostapd.conf, or perhaps sending me their hostapd.conf if they know that an iPad *can* connect to theirs.

(Note, that I had to take [HT40+] out of my ht_capab= section in order for the AP to appear on my MacBook Pro at all.)

Here is my hostapd.conf with comments removed:

interface=wlan0
driver=nl80211
logger_syslog=-1
logger_syslog_level=2
logger_stdout=-1
logger_stdout_level=2
dump_file=/tmp/hostapd.dump
ctrl_interface=/var/run/hostapd
ctrl_interface_group=0
ssid=Kaon v-OSK AP
country_code=US
hw_mode=a
channel=44
beacon_int=100
dtim_period=2
max_num_sta=255
rts_threshold=2347
fragm_threshold=2346
macaddr_acl=0
auth_algs=1
ignore_broadcast_ssid=0
wmm_enabled=1
wmm_ac_bk_cwmin=4
wmm_ac_bk_cwmax=10
wmm_ac_bk_aifs=7
wmm_ac_bk_txop_limit=0
wmm_ac_bk_acm=0
wmm_ac_be_aifs=3
wmm_ac_be_cwmin=4
wmm_ac_be_cwmax=10
wmm_ac_be_txop_limit=0
wmm_ac_be_acm=0
wmm_ac_vi_aifs=2
wmm_ac_vi_cwmin=3
wmm_ac_vi_cwmax=4
wmm_ac_vi_txop_limit=94
wmm_ac_vi_acm=0
wmm_ac_vo_aifs=2
wmm_ac_vo_cwmin=2
wmm_ac_vo_cwmax=3
wmm_ac_vo_txop_limit=47
wmm_ac_vo_acm=0
ieee80211n=1
ht_capab=[SMPS-STATIC][GF][SHORT-GI-20][SHORT-GI-40][TX-STBC][RX-STBC123]
eapol_key_index_workaround=0
eap_server=0
own_ip_addr=127.0.0.1

Any ideas?

-Joshua