Autority Check - SD

Hi,

I need check autority for the transaction:

VA01 / VA02

VA41 / VA42

VA21 / VA22

VLN01N

For that i use the code :

AUTHORITY-CHECK OBJECT 'ZAGENCE'

ID 'AGENCE' FIELD xxxx. ('xvbak-vkbur. i don't know...)

ID 'ACTVT' FIELD '01'.

IF sy-subrc ne 0.

MESSAGE...

ENDIF.

When an user want save in this transaction, he check the autority (su01 profile) and if he has not the autority they are an error message.

I need to know where i can implemented thid code for these transactions?

Thank you for your help and your reply.

Spawnrad