Crystal Reports problem with parameter

Message

   I set up the parameter to run the report with the name os system, assignee,
First in the SELECT EXPERT,  I set the formula as below:

Date({Command.CreatedDateTime}) in {?StartDate} to {?EndDate} and

(({?Category} = "ALL") or ({?Category} = {Command.Category})) and
(({?Service} = "ALL") or ({?Service} = {Command.Service})) and
(({?SubCategory1} = "ALL") or ({?SubCategory1} = {Command.SubCategory1}))

but after refesh, run the report, it jsut display  2 blank pages . IT doesn't active with the paramers. I don't know why?

Lasy time I thought the Crystal version has problem, I uninstall and reinstall , but still the same problem.

Or the problem because of the query?

My query is:
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select     c.ParentPublicID, c.incidentgroup, c.resareaoffailure,  
              c.resAreaOfFailureDetail,   a.CreatedDatetime, a.ChooseContact, 
              a.requestorDisplayName, a.TypeOfRecord as ServiceType,
              a.Impact, a.Urgency, a.Priority, 
              a.Description as WorkOrderDescription, a.Status,
              b.assignedTo, b.acknowledgedDateTime, b.ResolvedDateTime, 
              b.Notes, b.ResolutionNotes

from         serviceDesk a
FULL OUTER JOIN   task b
ON            a.ServiceDeskID = b.ParentPublicID 
                and   a.requestorDisplayName = b.SDInitiatior 
                and   a.TypeOfRecord = b.ParentServiceDeskType 

FULL OUTER JOIN timerecord c
ON           c.ParentPublicID  IN
                        (SELECT distinct ParentPublicID 
                                    FROM timerecord 
                         ) 
                 and  a.ServiceDeskID = c.ParentPublicID   

WHERE    a.CreatedDateTime between '2011-01-01' and getdate()
                and c.incidentgroup  in ('AOS', 'Tele')
                and c.ParentPublicID is not null

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Anyone can help me, please ! Thanks in advance.