Just bought a homeplug and a homeplug wireless extender (Maplin > Powerline 85Mbps 4-Port Switch with Wireless Access Point) and connected them up to my white DG834GT and I'm having a nightmare trying to get the wireless extender to duplicate the same settings as the DG834GT.

Currently I've got a network cable coming from the DG834GT into a homeplug downstairs and upstairs I've got the homeplug wireless extender.
I can ping the actual extender from my laptop and enter the configuration pages but I cannot seem to get the extender to give me a better wireless signal upstairs.
I've set the SSID, channel, security (WPA-PSK) and the subnet masks so they are the same on both.
Am I missing anything obvious?