PySide / Shiboken compilation error raised during cmake

Question

I am trying to install the new version of PySide (1.2. ~) On OS X 10.7.5 in virtualenv.

I follow the commands posted on the github page, however at compile time I get this error:

/opt/local/include/QtCore/qnamespace.h:9:10: fatal error: '../QtCore/qnamespace.h' file not found 

and then installation / compilation stops:

 make: *** [all] Error 2 error: Error compiling shiboken 

How to install PySide and solve this problem?