Crystal Reports possible to abort if no data found

Message

     CR 2008 

my report uses 
~1 SQL based table, "EMPLOYEE"
~1 excel spreadsheet, "Table"
~1 parameter WeekEndDateAsDate
~2 formulas
  @LastDateSaturday formula says if parameter 
    WeekEndDateAsDate entered is not a Sat, move out to the next Sat.
  @FirstDateSunday formula says back up to the Sunday prior to 
     @LastDateSaturday
~Record Select :
{Table_.for_Wk_Ending} >= {@FirstDateSunday} and
{Table_.for_Wk_Ending} <= {@LastDateSaturday} and
not ({EMPLOYEE.DEPARTMENT_ID} in ["10A", "10B", "30D"])

this report normally takes about 5 minutes to run.
If accounting forgets to enter the data one week into the excel table and someone tries to run the report for that week, it runs and runs and runs forever and finally returns zero hours paid.

Is there anyway to make the report look at the excel table first and if the @LastDateSaturday is not found abort the process? 
 and maybe even give the user a message that there are no entries for that date found!

Edited by carstowal - 14 Dec 2010 at 4:26am