How to filter rdlc report data using parameter

Hi,

I am using simple rdlc report to display student information data. I added parameters successfully tried all of the blogs sites but can't figure out what problem i am having following is my code:

private void button1_Click(object sender, EventArgs e)
{
DataSet1TableAdapters.studentTableAdapter adapter = new DataSet1TableAdapters.studentTableAdapter();
DataSet1.studentDataTable table = new DataSet1.studentDataTable();
adapter.FillBystudentname(table, textBox1.Text);

ReportDataSource mydatasource = new ReportDataSource("DataSet1.student", (DataTable)table);
this.reportViewer1.LocalReport.DataSources.Clear();
this.reportViewer1.LocalReport.DataSources.Add(mydatasource);
ReportParameter p1 = new ReportParameter(" ReportParameter1", comboBox1.SelectedValue.ToString());

this.reportViewer1.LocalReport.SetParameters(new ReportParameter[] { p1 });
this.reportViewer1.RefreshReport();

}

My parameter name is ReportParameter1

The error is coming "The ReportParameter1 is missing a value" can anyone help me out.