How to generate random values Iin random rows pl sql

I have this function and i want different row numbers between (4,8) for example. but it always returns me 4..

How can i have different row numbers every time?

CREATE OR REPLACE FUNCTION CUSTOMERS_DATA(
      P_MIN_CUSTOMERS NUMBER,
      P_MAX_CUSTOMERS NUMBER)
    RETURN NUMBER AS
    N PLS_INTEGER;
    CUSTOMER_DATA_ID NUMBER;
  BEGIN
    N := dbms_random.value(P_MIN_CUSTOMERS,P_MAX_CUSTOMERS);
    FOR LOOP_COUNTER IN 1..N
    LOOP
      CUSTOMER_DATA_ID := ADD_CUSTOMERS(dbms_random.string('X',10),
                                                 dbms_random.string('X',30),
                                                 dbms_random.string('X',10));
    END LOOP;
    RETURN CUSTOMER_DATA_ID;
  END CUSTOMERS_DATA;

DECLARE
I_ITEMS_ID NUMBER;

BEGIN 
  DELETE FROM MINI_ERP.ITEMS;

   I_ITEMS_ID := MINI_ERP.ITEMS_DATA(5,10);
END;