Networking Problem Advice Needed

I have a strange problem with if networking & wondered anyone could help.
I have a 50' long room & at the top end I have a Super Hub Router, at the bottom end I have my Computer which is connected Wirelessly to my Router. Further along in my garden I have an enclosed area with TV & a WD TV Live Hub. The WD Hub would not pick up the signal from my router so halfway between the two I installed a Netgear Range Extender, with a wi-fi adaptor connected to the WD Hub. This still barely connected to my WD Hub. So I tried taking out the Range Extender & connecting via Powerline Home Plugs (One to my Router & One To the WD Hub) this however didn't work. So I connected a Powerline Home Plug to the Range Extender & one in the Garden & got a perfect signal. What I can't work out is if I turn the Range Extender off I get no signal to the WD Hub.

If all your trying to do is connect the device in your garden with the home network try setting up a wireless bridge with directional antennas if its really far. I recommend getting a wifi router that is compatible with ddwrt (google it) and that has the ability to connect external antennas.