Webi Charts are not exported to xlsx format

Hi,

i set up a bi4.1 sp2 platform on a windows 2008 server.

With my former bi4.0 sp5 platforms i had the same issue:

webi document charts are not visible when the document is exported to the xlsx format.

i´im surprised i cańt find anything on the subject on the web.

am i missing something obvious?

thanks

xavier