Not all variables bound in PL SQL function

I having this console output in oracle's sql developer

> ORA-01008: no todas las variables han sido enlazadas ORA-06512: en
> "CIUDADANOS.CIUD_UTILIDADES_PKG", línea 183
> 01008. 00000 - "not all variables bound"
> *Cause:
> *Action:

The problem may be in the following line

OPEN l_temp FOR l_query USING fecha_val, departamento_val, localidad_val, edad_val, destinatario_val;

But when looking at all the variables used in the SQL query

This is the complete function

FUNCTION OBTENER_NOTIFICATIONS(fecha_val IN DATE, departamento_val IN NUMBER, localidad_val IN NUMBER, edad_val IN NUMBER, destinatario_val IN VARCHAR2)
RETURN VARCHAR2
AS
    l_query      VARCHAR2(2000);
    l_result     VARCHAR2(4000);
    l_temp       SYS_REFCURSOR;
    l_row        NOTIFICATIONS%ROWTYPE;
BEGIN
    l_query := 'SELECT * FROM NOTIFICATIONS WHERE ' || 
               '(:fecha_val >= NOTIFICATION_DATE_FROM) AND ' ||
               '(:fecha_val < NOTIFICATION_DATE_TO) AND ' ||
               '((DEPARTMENT_ID = :departamento_val)) AND ' ||
               '((LOCALITY_ID = :localidad_val)) AND ' ||
               '(:edad_val >= AGE_FROM) AND ' ||
               '(:edad_val < AGE_TO) AND ' ||
               '((RECIPIENTS = :destinatario_val) OR (RECIPIENTS = ''both''))';
    OPEN l_temp FOR l_query USING fecha_val, departamento_val, localidad_val, edad_val, destinatario_val;
    LOOP
        FETCH l_temp INTO l_row;
        EXIT WHEN l_temp%NOTFOUND;
        l_result := l_result || '{"ID": ' || l_row.ID || ', "RECIPIENTS":"' || l_row.RECIPIENTS || '","AGE_FROM":' || l_row.AGE_FROM || ',"AGE_TO":' || l_row.AGE_TO || ',"DEPARTMENT":' || l_row.DEPARTMENT_ID || ',"LOCALITY":' || l_row.LOCALITY_ID || ',"MESSAGE_TITLE":"' || l_row.MESSAGE_TITLE || '","MESSAGE_BODY":"' || l_row.MESSAGE_BODY ||'","ATTACHMENT_TYPE":"' || l_row.ATTACHMENT_TYPE || '","ATTACHMENT":"' || blob_to_base64(l_row.ATTACHMENT) || '","NOTIFICATION_DATE_FROM":"' || l_row.NOTIFICATION_DATE_FROM || '","NOTIFICATION_DATE_TO":"' || l_row.NOTIFICATION_DATE_TO || '","SEND_BY_EMAIL":"' || l_row.SEND_BY_EMAIL || '","CREATED_AT":"' || l_row.CREATED_AT || '","UPDATED_AT":"' || l_row.UPDATED_AT || '","DELETED_AT":"' || l_row.DELETED_AT || '"}';
    END LOOP;
    IF l_temp%ISOPEN THEN
        CLOSE l_temp;
    END IF;
    RETURN l_result;
END;

You are using positional binding, so you need to ensure that every bind has a variable associated with it in the exact order/position. It's not looking at the names. You'll need to double the fecha_val and edad_val binds:

l_query := 'SELECT * FROM NOTIFICATIONS WHERE ' || 
               '(:fecha_val >= NOTIFICATION_DATE_FROM) AND ' ||
               '(:fecha_val < NOTIFICATION_DATE_TO) AND ' ||
               '((DEPARTMENT_ID = :departamento_val)) AND ' ||
               '((LOCALITY_ID = :localidad_val)) AND ' ||
               '(:edad_val >= AGE_FROM) AND ' ||
               '(:edad_val < AGE_TO) AND ' ||
               '((RECIPIENTS = :destinatario_val) OR (RECIPIENTS = ''both''))';
    OPEN l_temp FOR l_query USING fecha_val, fecha_val, departamento_val, localidad_val, edad_val, edad_val, destinatario_val;