home button not working after back housing change

Hello, this is my first question. I have an iphone 3g with problem on home button.

I wanted to change the back housing and i ordered from ebay (model A1303, yes it is for 3gs but i didn't knew it then).

I started the process but i made one mistake, i put the dock under the bezel and the case had gap between it and the bezel. I opened iphone and the home button didn't work.

I didn't noticed my mistake with the dock and tried to solder the home button with wires to the dock. No success , only a thick layer of solder left at the dock.

After this, i understood my mistake with dock-bezel and fixed it. The home button didn't worked and i thougth it was damaged so i ordered a new one from ebay. I changed it (digitizer come off) and home button still not working.

I "touched" the dock's two metalic sockets (where home button supposed to connect to) with a wire and iphone acted like home button pushed, so dock is ok.

I put two pieces of foil between home button and dock and nothing happened...

So, where is my problem ? Home button is faulty ? or the back housing case is different from 3g and it doesn't allow, with some way, home button to reach the dock's sockets ? I tried to lift the two metalic pieces at the back of home button.