Notify can only use for once?

Hi! I don’t know if there’s any step that I went wrong.

I place a notify named “Pause” at frame 50 and 100 (which the animation frame is from 0~100)

I create a custom event through that pause notify.

The first one work as expected, yet the second one is not going to work with some reason.

Even if I put a notify on the other animation montage it still won’t work.

I also try putting a new notify and set an event on it, that notify also won’t work.

Is there a step that went wrong?