Graphs not showing

HI, I've created a report based on a query. Due to the way the data is
displyed, I had to create a second query to group relevant information under
one single field. For example, one field would show value of assets allocated
into derivatives; another field assets allocated into real estate; and so on.
I wanted to create a pie chart so I ended up creating a query that put all
those values under one field, also createing another field to identify what
type of assets those values refer to. Then, I tried to create a pie chart
showing those values. The pie chart will be repeated for each company that I
need to report on, which will vary depending on the selection that will be
defined in the query. Everything seems to work fine. I can see the graphs
where I want to see them in Print Preview. However, when I actually print it,
the graphs come all blank. Then I tried using snapshot or pdf format. The
same thing happened: data outside the graph is displayed but the graphs are
blank. Does anybody know what could be the issue? I'm using Access 2007. Just
to clarify, the Link Master Field and the Link Child Fields are the same
name: Scheme name. The graph read from one query and the remaining of the
report from a second query which have the same fields.
Not sure if it is enough info. But any help will be much appreciated.
Cheers,