嵌套声明游标出错，ORA-01400解决方法

DECLARE   v_acc_month date;   CURSOR c1   IS      SELECT    b.part_no             || '  ,  '             || TO_CHAR (material.get_minor_wh_stock_qty (b.part_no, c.warehouse))                                                                  debit_item        FROM material.minor_material b, public_mgr.warehouse c       WHERE c.material_flag = 'Y'         AND c.cost_flag = 'Y'         AND material.get_minor_wh_stock_qty (b.part_no, c.warehouse) < 0;BEGIN      FOR c1_rec IN c1      LOOP         :text1 := :text1 || c1_rec.debit_item || CHR (10) || CHR (13);      END LOOP;      DECLARE         vcount       NUMBER       := 1;         vserial_no   VARCHAR2 (4);         CURSOR c1         IS            ...      BEGIN         FOR c1_rec IN c1         LOOP            INSERT INTO material.minor_materialiohis                        (part_no, cday, CATEGORY,                         iotype, qty, internal_sheetno,                         dept, part_name,                         serial_no, unit,                         deliveryed, origin_qty,                         stock_position, batch_no                        )                 VALUES (c1_rec.part_no, c1_rec.cday, c1_rec.CATEGORY,                         c1_rec.iotype, c1_rec.qty, c1_rec.internal_sheetno,                         c1_rec.dept, c1_rec.part_name,                         TO_CHAR (vcount, '099'), c1_rec.unit,                         c1_rec.deliveryed, c1_rec.origin_qty,                         c1_rec.stock_position, c1_rec.batch_no                        );            vcount := vcount + 1;         END LOOP;      END;END;