Chart conversion

[saskabush]

I have a large number of 2003 ppts with graphs created with msgraph
which need to be converted to 2007 pptx changing the graphs to excel
based, not msgraph based.

I have opened a new pptx file with desired "theme" and then "reuse
slides" to import the ppt file. Some graphs convert to excel datasheet
fine but others won't convert "one or more charts in this document
cannot be converted to the current Microsoft Office chart format". Any
ideas on why this might be happening?

thanks
perplexed