I was having the same problem and just got it to work.
First in WPTouch options in WordPress make sure you have your publisher id in the correct field. Make sure you also include 'pub-' before your id. You can also input your ad category if you want to see specific data for that ad.
Next, this is what was stopping my ads from showing, sign into your Google Adsense account. Click My Ads. On the left side make sure you have Mobile Content allowed or started up. If it is still under the More Products section it will not display.. you need to turn on that feature.
Like BraveNewCode said.. WPTouch takes care of the rest.