GPO for an OU

Hi,

I have a single domain AD structure like this: All users are in users folder, there are global security groups which includes these users. And the security groups are moved to different OU’s.

For one of this OU’s i want to apply a Logon script. But when i set it it doesn’t work.
To make it work i must move the users to that OU one by one. Then it works.

Do you have any idea, that i can set a GPO for the OU’s in this structure.