Syntax error at or near ( error - error code 42601 - npgsql

Question

I am migrating a c# application from sql server express edition to postgresql using npgsql 4.1.3.1. However I am getting the syntax error 42601 whenever i try to add row a databound datagridview programmatically. I had a look at the update command generated by npgsqlcommandbuilder and it includes an extra parenthesis at the end. ("pfuppersalarylimit" = #p133)) of the command. Any help shall be highly appreciated.
`NpgsqlConnection con;`
NpgsqlCommand sqlcmd;
NpgsqlCommandBuilder builder;
DataSet ds;
BindingSource bs = new BindingSource();
public frmEmployee()
{
string str = Properties.Settings.Default.connectionstring; //.Settings.connectionstring2;
con = new Npgsql.NpgsqlConnection(str); //
InitializeComponent();
}
private void frmEmployee_Load(object sender, EventArgs e)
{
string sql = "Select * from employee where company_code='S00159' order by rownumber";
ds = new DataSet();
da = new NpgsqlDataAdapter(sql, con);
builder = new NpgsqlCommandBuilder(da);
da.Fill(ds);
bs.DataSource = ds;
bs.DataMember = ds.Tables[0].ToString();
DataGridView1.DataSource = bs;
}
private void addemployee_Click(object sender, EventArgs e)
{
int start_row_number;
int pos1;
try
{
if (DataGridView1.Rows.Count == 0)
{
pos1 = 0;
start_row_number = 1; // added on 15/10/2011
}
else
{
pos1 = DataGridView1.CurrentCell.RowIndex + 1;
start_row_number = Convert.ToInt32(DataGridView1.Rows[pos1 - 1].Cells["rownumber"].Value) + 1;
}
DataRow employeeRow = ds.Tables[0].NewRow();
string emplcode = companyInfo.company_code.Substring(1, 1) + classMisc.genEmployeeCodeNew(); // just a random number
employeeRow["company_code"] = companyInfo.company_code.Trim();
employeeRow["employee_code_no"] = emplcode;
employeeRow["srno"] = classMisc.getsrno();
employeeRow["flag"] = true;
employeeRow["rownumber"] = start_row_number; // pos1
employeeRow["mobile"] = 0;
employeeRow["aadhar"] = 0;
employeeRow["pfuppersalarylimit"] = 0;
ds.Tables[0].Rows.InsertAt(employeeRow, pos1);
}
catch (Exception ex)
{
MessageBox.Show(ex.Message + "error 1");
}
}