Internet sharing over WiFi from iMac to iPad/iPod Touch isn't working

Hello,

firstly, I'm french, and my english is probably not very good.

I've tried to share internet connection from my iMac (under OS X 10.6.8 Snow Leopard) to my iPod a long time ago. It worked. But suddenly, it stopped to work. No update, no software installation, no settings' changes...

I also tried to share internet connection on another Mac, a Macbook Pro under Snow Leopard. It worked. I tried with my iPad mini a few weeks later, it didn't work. Then, I tried with my iPod touch : no result. I've checked the WiFi settings on both devices.There is only IP and Subnet mask, while when it worked, there was full settings. My iPod is running iOS 5.0.1 and my iPad mini has iOS 6.1.2. They are both jailbroken. My iPad's WiFi settings are ajusted thus :

IP Adress : DHCP

169.254.76.12

Subnet mask : 255.255.0.0

Router : Blank

DNS : Blank

Search domains : Blank

Client ID : Blank

HTTP Proxy : Disabled

My iMac Ethernet settings are ajusted thus :

Connected

Ethernet is actually online and has the IP adress 192.168.1.16.

Configuring IPv4 : DHCP

IP Adress : 192.168.1.16

Subnet : 255.255.255.0

Router : 192.168.1.1

DNS server (gray) : 192.168.1.1, 192.168.1.1

Search domains (gray) : home

The Internet Sharing works with another iMac, running OS X Lion, but I just want to have it on my iMac Can you help me, please ? I'm really disappointed.