Configure WIFI for 802.11a

[linuxlifer2]

I'm trying to configure my WNIC for 802.11a. According to lspci I have a:
03:00.0 Network controller: Intel Corporation Centrino Advanced-N 6205 (rev 34)

According to iwlist it supports 32 channels:
iwlist wlan0 frequency
wlan0 32 channels in total; available frequencies :
Channel 01 : 2.412 GHz
Channel 02 : 2.417 GHz
Channel 03 : 2.422 GHz
Channel 04 : 2.427 GHz
Channel 05 : 2.432 GHz
Channel 06 : 2.437 GHz
Channel 07 : 2.442 GHz
Channel 08 : 2.447 GHz
Channel 09 : 2.452 GHz
Channel 10 : 2.457 GHz
Channel 11 : 2.462 GHz
Channel 36 : 5.18 GHz
Channel 40 : 5.2 GHz
Channel 44 : 5.22 GHz
Channel 48 : 5.24 GHz
Channel 52 : 5.26 GHz
Channel 56 : 5.28 GHz
Channel 60 : 5.3 GHz
Channel 64 : 5.32 GHz
Channel 100 : 5.5 GHz
Channel 104 : 5.52 GHz
Channel 108 : 5.54 GHz
Channel 112 : 5.56 GHz
Channel 116 : 5.58 GHz
Channel 132 : 5.66 GHz
Channel 136 : 5.68 GHz
Channel 140 : 5.7 GHz
Channel 149 : 5.745 GHz
Channel 153 : 5.765 GHz
Channel 157 : 5.785 GHz
Channel 161 : 5.805 GHz
Channel 165 : 5.825 GHz

However when I go to set it anywhere in the 5 GHz band I get this error:
iwconfig wlan0 mode ad-hoc
iwconfig wlan0 freq 5.18G
Error for wireless request "Set Frequency" (8B04) :
SET failed on device wlan0 ; Invalid argument.
iwconfig wlan0 channel 36
Error for wireless request "Set Frequency" (8B04) :
SET failed on device wlan0 ; Invalid argument.

There are no new messages in /var/log/messages.
With Mode:Managed there is no issue.
There Mode:Ad-hoc and channels 1-11 are accepted by the iwlwifi driver.
Any troubleshooting ideas would be very much appreciated.

I'm using:
Fedora 15 and have tried these kernels:
2.6.38.6-26.rc1.fc15
2.6.42.3-2.fc15
2.6.42.9-1.fc15

[Rubberman]

Have you tried a newer driver? You can find them on the Intel web site.