how to count the number of records in each dataset?

Hi frnz,

I have a report that having 5 datasets that is using a single report.

here i want to count the no of records of each datasets in my report how would i do this.

i have written this expression 

CountRows("Dataset1") but its not working 

its showing error like below.

The value expressio for the text box has a scope parameter that is not valide for an aggregate function
the scope paramaeter must be set to a string constant that is equal to either the name of a  conatining 
group ,the name of a conatining data region, or the name of the dataset.

Is there any other expression is there can you please help me out for this..

Thanks!