Problem on layout and graph pie chart

[scwk]

hi
need help to display correctly my report
i've insert 2 subreport on a main report
so,i 've a field of client name on the detail section on the top , then comes the 2 subreport on the same level
on the design view i placed my objects correctly but when i preview the report the 2 subreport hide the client name field. on the first page its correctly displayed but the next 40 page, the client name field is hidden.
I want to know what's the problem and how to solve this.

one more question
Can i change the label field on the graph pie chart?

Please reply me
Many thanks
scwk