[TYPO3-mvc] Tx_Extbase_Persistence_ObjectStorage problem

[Eat Dimanche]

Hi,

 >> I have two tables have relationship to each other: "member" & 
"service". For each member can have 1..* on service.

 >> In table member I have stored the services separately by comma.
For example:

 >> table member
-----------------------
uid	name	service
-----------------------
1	Sok	1,2
2	Sao 	2,3
3	Dimanche 4
-----------------------

 >> table service
-------------
uid	name
-------------
1	AA
2	BB
3	CC
4	DD
5	EE
-------------

 >> I am working in the backend it works properly. But now, I would like
to update service in the frontend. I can't. The value always be null in 
database when I updated.
 >> For editing form I am using multiple selection box. For property 
service is assigned type as Tx_Extbase_Persistence_ObjectStorage, also 
method getter and setter same relatedPosts.


Could anyone help me for this problem?
Thanks a lot.

Best regards,
Dimanche