Currently, the Lifeprint 3x4.5 printer with WiFi support can only use 2.4Ghz connection points. Some people have set up their routers with two connection points: one for the 5.0Ghz channel and a separate one for the 2.4Ghz channel. WiFi configuration for the printer is copied from your phone. So, if your phone is currently connected to a 5.0Ghz connection point, the configuration will fail, as it cannot use that channel. In this case, the printer shows you the available connection points it sees that using the compatible channel. Please connect your phone to an available 2.4GHz connection point, and try the printer WiFi configuration once again.
Not that this is only for Lifeprint 3x4.5 printers, all other Lifeprint printers are Bluetooth only and don't use WiFi.