Getting An Access Point To Communicate With A Router?

My basement doesn't get a good wireless signal. It doesn't affect my computer since it's hardwired via a couple of Asoka PlugLinks. However, I've always had bad signal reception from my main router which is two floors above. Because of this, I was rarely able to connect my Wii to the internet and am now unable to connect my Wii U to it either.Recently I purchased a new wireless router (a Linksys e1200n) to speed up the network. So, having a spare router (the old router: a Linksys WRT54G), I decided to try to convert it to an access point in the basement so the Wii U could finally get a stable internet connection (it's very picky about signal strength for some reason). I reset the old router and followed some instructions on how to make it an access point instead of a router. Once it was configured I bought another Asoka PlugLink and placed the WRT54G in the basement. I connected the PlugLink to the wall outlet and connected the Ethernet cable to LAN port 1 on the WRT54G. I thought everything would be fine, but then the problems came.

My Wii U was unable to connect to it. I also tested a couple of laptops and they were able to connect to it, but they couldn't access the internet. I assumed maybe distance from the main router was the cause(a PlugLink is connected from LAN port 1 on the back of the main router into a wall outlet, linking other PlugLinks to it), but my computer's PlugLink is in the same room and has no problems connecting.