Error in monthly report code use of crystal report?

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SQL

C#3.5

I want to make monthly report on button click event and display through crystal report.
tc_np = tab control name
tbprint = tab name where i put crystalreportviewer.
mnt = is crystal report where i define or design according table of patient_info
crv = is crystalreportviewer name.

private void mntbtn_Click(object sender, EventArgs e)
        {
            tc_np.SelectedTab = tbprint;
            try
            {
                cn.Open();
                DataSet ds2 = new DataSet();
                //SELECT * FROM MyTable WHERE DATEDIFF(mm, MyDateColumn, GETDATE()) = 0
                mnt m = new mnt();
                OleDbCommand cmdmnt = new OleDbCommand("select * from patient_info where DATEDIFF(m, E_date, DATE())=0",cn);
                OleDbDataAdapter da = new OleDbDataAdapter(cmdmnt);
                da.Fill(ds2, "patient_info");
                m.SetDataSource(ds2.Tables["patient_info"]);
                crv.ReportSource = m;
                crv.RefreshReport();
                cn.Close();
            }
            catch (Exception p)
            {
                MessageBox.Show(p.Message,"error",MessageBoxButtons.OK,MessageBoxIcon.Error);
            }

        }

error at:

da.Fill(ds2, "patient_info")

error: "no value given for one or more required parameters"


What I have tried:

i tried chages in date(), give condition for as Datediff(mm,E_date,Date())=30, and etc.