.NET Oracle SP call errors ORA-00604 and ORA-01001 when pass

CREATE OR REPLACE PROCEDURE BLAH_SEARCH
  (start_index NUMBER,
   num_rows NUMBER,
   total_num_rows OUT NUMBER,
   results OUT sys_refcursor)

AS
  sql_stmt VARCHAR2(4000);
  results1 sys_refcursor;
BEGIN
  sql_stmt := '
  WITH
    filter_set AS (
      SELECT
          ROWNUM ri,
          e.*
        FROM blah e
        WHERE 1=1 /*some conditions*/
      ORDER BY /*order*/
    ),
    filter_set_r AS (
      SELECT fs.*
        FROM filter_set fs
        WHERE ri BETWEEN :start_row AND :end_row
    )
  SELECT
      (SELECT COUNT(*) FROM filter_set) total_num_rows,
      CURSOR(
        SELECT *
          FROM filter_set_r fs
          ORDER BY ri ASC
          ) results_cur
    FROM dual
  ';

  OPEN results1 FOR sql_stmt
    USING site_id, start_index, start_index + num_rows - 1;
  FETCH results1 INTO total_num_rows, results;
END;