Problems closeing subscriptions

Hi;

I'm moderate a majordomo list running on version 1.9.4

I recently decided to make subscriptions by approval only.

It works, but every now and then someone subscribes without the approval 
process kicking in.

I have this line set thusly in my config:

		subscribe_policy=closed+confirm

Is there anything else I need to do?

Does anyone know anything about this issue?

Thanks in advance for any information!

Steve