Vista - report viewer - project defined dataset

Hello,

i have the following issue:

i setup a dataset in my project in order to use it for a report (report
viewer control).
with the wizard for a new report, i created "Dataset1".

in the implementation that i found on internet, the programmer links a new
dataset with the report before displaying the data.
the dataset used for the report is then an other one than "Dataset1".

But in my case, i want to use "Dataset1".
but program says that it is empty. if i do a "preview data" with my
"dataset1", i have rows ?????

any idea ?

thanks
ELE