crystal report error passing parameter

What i am doing wrong?
I have a report with two(2) tables and a parameter field.

On my app i have the following (according to microsoft 101C# samples:Windows forms: Using Crystal Reports)

Code:

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CrystalDecisions.Shared.ParameterValues pvCollection =new CrystalDecisions.Shared.ParameterValues();
CrystalDecisions.Shared.ParameterDiscreteValue pdvCustomerName = new CrystalDecisions.Shared.ParameterDiscreteValue();
ReportDocument rptcuentaespecifica =new ReportDocument();
try
  {
        rptcuentaespecifica.Load(@"..\..\rptespecifica.rpt");
        pdvCustomerName.Value = cbofilename.Text;
        pvCollection.Add(pdvCustomerName);
        rptcuentaespecifica.DataDefinition.ParameterFields["@Descripcion"].ApplyCurrentValues(pvCollection);
        crvBasic.ReportSource = rptcuentaespecifica;
        crvBasic.Zoom(2);
}

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but nothing works. The report bring me all data on the table and i just want the one selected on cbofilename.text
How do i pass a parameter to a report?

Any help

Try instantiating your report document.

Code:

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CrystalDecisions.Shared.ParameterValues pvCollection =new CrystalDecisions.Shared.ParameterValues();
CrystalDecisions.Shared.ParameterDiscreteValue pdvCustomerName = new CrystalDecisions.Shared.ParameterDiscreteValue();
rptespecifica rpt=new rptespecifica();
try
  {
        pdvCustomerName.Value = cbofilename.Text;
        pvCollection.Add(pdvCustomerName);
        rpt.DataDefinition.ParameterFields["@Descripcion"].ApplyCurrentValues(pvCollection);
        crvBasic.ReportSource = rpt;
        crvBasic.Zoom(2);
}

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