When I Am Passing Sql Parameter Arrey As Parameter To Wcf Service In Is Giving Error

protected void btnnextpersdetls_Click(object sender, EventArgs e)
    {
SqlParameter[] _params = { new SqlParameter("@UserName","kotlanaveen23@gmail.com"),new SqlParameter("@password","xswqaz")};
DataSet ds1 = new DataSet();
ds1 = objl.fnExecuteDataSet("hrrec", "T", "sp_GetEmpPersonalDetails", _params);
}


service method

public DataSet fnExecuteDataSet(string schema, string connect_Test_or_Production, string p, params SqlParameter[] Parameters)
    {
        // throw new NotImplementedException();
        try
        {
            if (fnOpenConnection(schema, connect_Test_or_Production) == true)
            {
                _objDataSet = new DataSet();
                _objSqlDataAdapter = new SqlDataAdapter();
                _objSQLCommand = new SqlCommand();

                _objSQLCommand.Connection = _objSQLConnection;
                _objSQLCommand.CommandType = CommandType.StoredProcedure;
                _objSQLCommand.CommandText = p;

                foreach (SqlParameter objParamaeter in Parameters)
                {
                    _objSQLCommand.Parameters.Add(objParamaeter);
                }

                _objSqlDataAdapter.SelectCommand = _objSQLCommand;
                _objSqlDataAdapter.Fill(_objDataSet);

                return _objDataSet;
            }
            else
            {
                return null;
            }
        }
        catch (SqlException dbEx)
        {
            return null;
        }
        catch (Exception ex)
        {
            return null;
        }
        finally
        {
            _objDataSet = null;
            _objSqlDataAdapter = null;
            _objSQLCommand = null;
            fnCloseConnection();
        }
    }