Tilt Controls in Portrait mode

Hi.

I am a game designer that has just started using Construct 2 seriously and have almost zero programming skills. I am currently making a mobile game with tilt controls. I have run into the following problem and although I read through the forums and the documentation, I still have not found a solution to my seemingly simple problem (could be down to inexperience).

I have locked the game in portrait mode and have added touch controls. My goal is to make my sprite move left and right by tilting the phone left and right in portrait mode. Unfortunately, although the controls seem to work when I hold the phone in landscape mode, in portrait they are a bit erratic and work half the time.

Can anyone help me on this subject or point me to a post that I may have missed? I include a screenshot of my event sheet. Thanks in advance for your help.

<img src="http://i.imgur.com/Wnsbpeg.png" border="0" />

UPDATE

Apparently, if you replace Touch.Gamma with Touch.Beta, the controls work fine!!

Could someone explain to me with this is so (it will probably be useful in the future)? Isn't touch.gamma supposed to be left/right and touch.beta front/back?

Hello I am working on setting up my game with a similar control scheme. I have been having trouble finding a guide or anything that shows how you go about this. Do you have any updates on your game or offer any advice on setting up for a mobile device using tilt controls to move the character in portrait mode. I know you posted this a long time ago, but I just stumbled upon it today. Thanks for the time.