Same thing happens to me.
I think you can only subscribe to a thread when you have the post window open, at the moment. I haven't tried though. Check "Subscribe and receive email notification of new replies". It's located at the bottom of the post box.
I think you can only subscribe to a thread when you have the post window open, at the moment. I haven't tried though. Check "Subscribe and receive email notification of new replies". It's located at the bottom of the post box.