ucreate_og + og_notifications

Hello,
In OpenAtrium, I actived module "og_notifications" to automatically subscribe users to a group of content types.
When I create a user from the group, notifications are not automaticlly generated.
I went to the mysql system table and I changed weight of module "ucreate_og" : -10 to 0.
Afterwards, when I create user in the group, it works properly and subscriptions are automatically generated.
Do you think this is a good solution given that e change this system? Why did you put at -10? That there an impact on the rest of the operation?
Thanks for you response.
Cordially,