sql server reproiting service 2005

Question

I am new to sql reporting service 2005. I am getting an error message
saying the 'command text' property is not 'initialized'.
Being a .net programmer, I know the comand text is the sql in text format
or a stored procedure is not being accessed.
This error occurs after I have setup a report manually and I have changed
the stored procedure that is being called or after I have made a modification
to the report.
Note: when I setup the report format initially myself, the report runs and
displays all the data I want to see.

Thus, can you make suggestions on what I can change and/or look at?

Thanks!