cannot view chart created in excel 2003 in excel 2007
 

we had just purchase a new computer with office 2007.
The problem is that whenever we wanted to view our previous report that had
graphs and chart in it (created using excel 2003) using the excel 2007 the
graph or chart cannot be viewed. but if it just containing text and table
then there is no problem.
how can we overcome this problems?