Cant add many rowitem for parameter fields in report

I use this code to add a item to parameter field in crystal report.

But i want to add many such item to that field but it only can add one.

I WANT TO ADD MANY ITEM TO A PARAMETER FIELD.,,,

Code:

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Dim param1Fileds As New CrystalDecisions.Shared.ParameterFields
        Dim param1Field As New CrystalDecisions.Shared.ParameterField

        Dim param1Range As New CrystalDecisions.Shared.ParameterDiscreteValue
        Dim param2Range As New CrystalDecisions.Shared.ParameterDiscreteValue
      Dim param3Range As New CrystalDecisions.Shared.ParameterDiscreteValue

        Dim param2Field As New CrystalDecisions.Shared.ParameterField

        param2Field.ParameterFieldName = "Field2" ' Parameter Name In Crystal Report
        param3Range.Value = "Manh dep trai hot boy1" ' value For Parameter Field"
        param2Range.Value = "Manh dep trai hot boy" ' value For Parameter Field"
        param2Field.CurrentValues.Add(param2Range)
        param2Field.CurrentValues.Add(param3Range)
       
        param1Fileds.Add(param2Field)
 
        CrystalReportViewer1.ParameterFieldInfo = param1Fileds 'to pass parameter inf.to CRV
        CrystalReportViewer1.ReportSource = CRYRpt1 ' Assign Report Source to CRV
        CrystalReportViewer1.Refresh()

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The red line is item which i want to add.

Moved To Reporting

Before adding the values set the ParameterField.EnableAllowMultipleValues property to True.