How do I Dynamically add and remove parameterfields from crystal reports

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C#

CrystalReports

I have created a Windows Forms project in C#.NET. I have also created a crystal report which is blank. I have dragged and dropped a Crystalrportviewer to windows forms. I am trying to populate it with text on click of button. Here is my code:-

private void button1_Click(object sender, EventArgs e)
{
    CrystalReport2 crt1 = new CrystalReport2();

    ParameterField prm1 = new ParameterField();

    prm1.Name = "Param1";
    prm1.PromptText = "Param3";
    prm1.ParameterValueType = ParameterValueKind.StringParameter;


    ParameterDiscreteValue pdm1 = new ParameterDiscreteValue();
    pdm1.Value = "hello";// textBox1.Text;

    prm1.CurrentValues.Add(pdm1);
    ParameterFields myParams = new ParameterFields();

    myParams.Add(prm1);
    crystalReportViewer1.ParameterFieldInfo = myParams;

    crystalReportViewer1.ReportSource = crt1;
    crystalReportViewer1.Refresh(); 
}

But it is showing blank report. Please help. Also I would Like to know how to remove parameter field dynamically from crystal reports. Thanks in Advance.