Background images missing after a M$ ppt import

Background images missing after a M$ ppt import

Hi. I've just import with success a m$ Office2003 ppt presentation (500k) into ZohoSow2.
However the backround image of each clip (on image for all the clips; image from PowerPoint Images Gallery) is missing

Is there specific preferences I've to enable before importing a ppt into Zoho ?
Regards
Philippe