Canon Pixma MX520 Series Online Manual page 453

Cannot Detect the Machine with the Wireless LAN: Check 3
Is the wireless LAN setting of the machine enabled?
Make sure that the Wi-Fi lamp of the machine is lit blue.
If the Wi-Fi lamp is off:
The wireless LAN setting of the machine is not activated. Activate the wireless LAN setting of the machine.
After activating the wireless LAN setting, click Back to Top on the Check Printer Settings screen to try to
set up the network communication from the beginning.
If the Wi-Fi lamp is lit:
Go to check 4.
Cannot Detect the Machine with the Wireless LAN: Check 4