Datasource.Insert(), Throws Object reference not set to an instance of an object Error

Question

I have been working on the new project and I have met this situation where I couldn't come out of it. The code is to insert data into DB.

ASPX file code: {

 <InsertParameters>
            <asp:Parameter Name="MilestoneName" Type="String" />
            <asp:Parameter Name="JobCodeID" Type="Int32" />
            <asp:Parameter Name="IsBODApplicable" Type="Boolean" />
            <asp:Parameter Name="JobCode" Type="String" />
            <asp:Parameter Name="SeqNo" Type="Int32" />
            <asp:Parameter Direction="InputOutput" Name="ErrNo" Type="Object" />
        </InsertParameters>

}

cs File code:

{

odsMilestones.InsertParameters.Clear();
                odsMilestones.InsertParameters.Add("MilestoneName", tbMilestoneName.Text);
                odsMilestones.InsertParameters.Add("JobCodeID", "0");
                odsMilestones.InsertParameters.Add("IsBODApplicable", chkBODApplicable.Checked.ToString());
                odsMilestones.InsertParameters.Add("JobCode", ddlToBeCompleted.SelectedValue);
                odsMilestones.InsertParameters.Add("SeqNo", tbSeqNo.Text);
                odsMilestones.InsertParameters.Add("ErrNo", null);
                odsMilestones.Insert();
                grvMilestones.DataBind();

}

Dataset Designer Code: {

public virtual object uSP_Milestone_Insert(string MilestoneName, global::System.Nullable<int> JobCodeID, global::System.Nullable<bool> IsBODApplicable, string JobCode, global::System.Nullable<int> SeqNo, ref global::System.Nullable<int> ErrNo) {
            global::System.Data.SqlClient.SqlCommand command = this.CommandCollection[2];
            if ((MilestoneName == null)) {
                command.Parameters[1].Value = global::System.DBNull.Value;
            }
            else {
                command.Parameters[1].Value = ((string)(MilestoneName));
            }
            if ((JobCodeID.HasValue == true)) {
                command.Parameters[2].Value = ((int)(JobCodeID.Value));
            }
            else {
                command.Parameters[2].Value = global::System.DBNull.Value;
            }
            if ((IsBODApplicable.HasValue == true)) {
                command.Parameters[3].Value = ((bool)(IsBODApplicable.Value));
            }
            else {
                command.Parameters[3].Value = global::System.DBNull.Value;
            }
            if ((JobCode == null)) {
                command.Parameters[4].Value = global::System.DBNull.Value;
            }
            else {
                command.Parameters[4].Value = ((string)(JobCode));
            }
            if ((SeqNo.HasValue == true)) {
                command.Parameters[5].Value = ((int)(SeqNo.Value));
            }
            else {
                command.Parameters[5].Value = global::System.DBNull.Value;
            }
            if ((ErrNo.HasValue == true)) {
                command.Parameters[6].Value = ((int)(ErrNo.Value));
            }
            else {
                command.Parameters[6].Value = global::System.DBNull.Value;
            }

}

I have debugged and tried to find the error. I couldn't. Please help.