SurfaceKeyboard doesn't open in Win7

Hey there,

i'm trying to integrate the SurfaceKeyboard into an existing program but this causes some problems..
When I try to open the Keyboard with setting the IsVisible property to 'True' nothing happens.

System.Windows.Input.Keyboard.Focus((IInputElement)sender);
SurfaceKeyboard.IsVisible = true;

I found out that the value of the property didn't change, so it's still 'False'.

In this post: 

http://social.msdn.microsoft.com/Forums/vstudio/en-US/c460ed52-dbde-4540-868a-bce0f1a906d7/show-numeric-keypad-in-windows-7-wpf-touch-application?forum=wpf

i've read that it should be possible to use the SurfaceKeyboard also in Win7..

Can anyone help me with this issue?

Right now I have installed VS2010 with Surface SDK 2.0 and Surface Runtime 2.0.

Thanks in advance!

e_card