Admob starting help needed.

Finally I’ve got AdMob up and running, showing ads on my android and iOS, in a banner form, but I can’t seem to be able to set it up for it to show at the bottom of my screen for some reason, it would seem that I need to “fine tune” it for each and every device, and that seems just wrong to me, I’m sure there is a simple way to get the banner to be placed at the bottom of the screen on all devices.

I’ve found so far that using:

local adX, adY = display.screenOriginX, display.viewableContentHeight; ads.show("banner",{x=adX,y=adY});

would work find for Galaxy SIII for example, and for iPhone 4S, but it would show about 100 pixels above the bottom of the screen for the iPhone 5…

Does someone have a solution for this?

Thanks,

Yuval.