help filtering data on runtime

[dicky18]

hi there i need some help in filtering data in crystal reports on runtime i have this code to filter who paid or not the guys who paid there is a date for them while who didnt its empty i want to filter to see on the peoplr eho didnt paid i.e the empty records
i have this code but missing

Dim Fltr
Dim str As String
Dim order As String


order = "{CustomerOrder.AmoundDue} <-----dont know what to put here


str = str + order
Me.CrystalReportViewer1.ReportSource = ".\CustomerInvoice.rpt"
Me.CrystalReportViewer1.SelectionFormula = str
Me.CrystalReportViewer1.RefreshReport()


thanks in advance and another code could help thanks