Cannot import PowerPoint Presentations with PowerPoint 2010

I have Openlp1.9.4 on Win 7 with pptx 2010 i can't import pptx

OpenLP Bug Report
Version: 1.9.4

--- Please enter the report below this line. ---

--- Exception Traceback ---
Traceback (most recent call last):
File "C:\Documents and Settings\raoul\My Documents\My Projects\openlp\trunk\build\pyi.win32\OpenLP\outPYZ1.pyz/openlp.core.lib.mediamanageritem", line 482, in onAddClick
File "C:\Documents and Settings\raoul\My Documents\My Projects\openlp\trunk\build\pyi.win32\OpenLP\outPYZ1.pyz/openlp.core.lib.mediamanageritem", line 534, in buildServiceItem
File "C:\Documents and Settings\raoul\My Documents\My Projects\openlp\trunk\build\pyi.win32\OpenLP\outPYZ1.pyz/openlp.plugins.presentations.lib.mediaitem", line 265, in generateSlideData
File "C:\Documents and Settings\raoul\My Documents\My Projects\openlp\trunk\build\pyi.win32\OpenLP\outPYZ1.pyz/openlp.plugins.presentations.lib.powerpointcontroller", line 132, in load_presentation
File "C:\Documents and Settings\raoul\My Documents\My Projects\openlp\trunk\build\pyi.win32\OpenLP\outPYZ1.pyz/openlp.plugins.presentations.lib.powerpointcontroller", line 80, in start_process
File "C:\Documents and Settings\raoul\My Documents\My Projects\openlp\trunk\build\pyi.win32\OpenLP\outPYZ1.pyz/win32com.client.dynamic", line 566, in setattr
AttributeError: Property 'PowerPoint.Application.Visible' can not be set.

--- System information ---
Platform: Windows-post2008Server-6.1.7600

--- Library Versions ---
Python: 2.6.2
Qt4: 4.6.1
Phonon: 4.3.1
PyQt4: