SQL reporting svcs: Multiple Datasets and stored procs: error?

[TOraptor]

I have a report that used different stored procs for different sections of the data.
eg. one table uses stored proc and the following table uses stored proc B.

I have a shared data source for each stored proc. In the Data tab i created datasets corresponding to each stored proc and i am loading the fields from each dataset into the report in the layout tab.

When i run my stored proc i get an error like:
"error while report processing. Query execution failed for dataset 'SurveyDB'. ExecuteReader: CommandText property has not been initialized"

Any ideas on how to get rid of this error.
Is it OK to have different datasets for different objects on the same report?

TIA