Recalling Reply Message

Scenario:
I received an email as a CC that was sent to multiple users. I replied to all. My boss then wanted to reply to me alone. She choose Reply and I was the only one there and then she wanted to recall the message. She did so and sent the next reply again just to me. Then she started receiving “message recall failure” to the people that were in the original email. If she did send the reply to them and only to me why is she getting the “message recall failure” for those people?