I have never tried to retrieve 2 tables from a stored proc that is bound to the report. I do return multiple tables from a stored proc and then set the datasource of the report (pulling the data vs pushing data).
I am assuming that you are selecting the data from both tables in the stored proc, but CR is only picking up the first one.
If the above is true, what I would try is to concatenate the 2 tables together and return just one. After all, one is the summary of the other, so you wouldn't be returning any more rows, actually fewer overall, but the table would be wider. You would use the summary information in your headers/footers and the detail in the detail...
HTH