Error using Acrobat portfolio SDK with Flash Builder

Hi all

I've been trying to customize a navigator portfolio for Adobe Acrobat X using Flash Builder 4.5. I was running this proyect as Navigator but I received the following Flash Player error:

TypeError: Error #1009: Cannot access a property or method of a null object reference.
at acrobat.navhost.app::SingleNavApp/set productConfig()[C:\dev\A10_1R1_Sandbox\Acrobat\Viewer\AcroView\Portfo lio\Flash\Libs\NavHostUtil\src\acrobat\navhost\app\SingleNavApp.as:333 ]
at com.adobe.app::AppPrefsBinding/productConfig()[C:\dev\A10_1R1_Sandbox \Acrobat\Viewer\AcroView\Portfolio\Flash\Libs\NavPreviewShared\src\com \adobe\app\AppPrefsBinding.as:93]
at com.adobe.app::AppPrefsBinding/refresh()[C:\dev\A10_1R1_Sandbox\Acrob at\Viewer\AcroView\Portfolio\Flash\Libs\NavPreviewShared\src\com\adobe \app\AppPrefsBinding.as:76]
at Function/()[E:\dev\4.x\frameworks\projects\framework\src\m x\binding\utils\BindingUtils.as:180]
at mx.binding.utils::ChangeWatcher/wrapHandler()[E:\dev\4.x\frameworks\p rojects\framework\src\mx\binding\utils\ChangeWatcher.as:557]
at flash.events::EventDispatcher/dispatchEventFunction()

I've installed Acrobat portfolio SDK into Flash Builder and I have followed the documentation of Building a Navigator from http://learn.adobe.com/wiki/display/PDFNAV/Building+a+Navigator