My experience, in crystal viewer, when you hit F5 it refreshes the report.
If the report uses parameters it prompts for using existing values for the params or changing the values.
For disecting the report, look at the report given to you, in the field explorer under parameter fields. You will either see 2 date params , or one date param set to allow a date range.
If you look inside the select expert you will likely see that the date range is being used to limit the data there.
Note that you will not be prompted for entering a value into a crystal parameter that has not been inserted into the report design somewhere.
E.g. just because you create a paramter in the Field Explorer does not mean you get the pop up when you run the report (or refresh the report with F5).
Edited by DBlank - 10 Nov 2011 at 4:02am