need to set ReportSource twice

See more:

C#

VB

CrystalReports

Hi I must write command "Crv.ReportSource = myreport" twice becouse in vs2013
for first time when execute program show all data and after second run it accept parameter. why?
how can i set Crv.ReportSourceby empty things like nothing or ...?

Dim myreport As New myRpt
Crv.ReportSource = myreport

myreport.RecordSelectionFormula = {TblPersonnel.PCode} = 1 
myreport.Refresh()

Crv.ReportSource = myreport
Crv.Refresh()

thanks