Which message was that? I am still using GTalk on my phone (Android 4.1, no updates in site, such a relic of a phone to be two years old right? Xperia S - 32GB of storage and a decent camera, so why no updates? It's STUPID)
I notice that people attempting to communicate via Hangouts (on their phone?) doesn't notify me in Talk. If I attempt to call someone who has Talk on their phone from my web browser (therefore using Hangouts), they never get any notification. I can therefore never get in touch with my brother, unless I call him using Talk from my phone.
If someone attempts to talk to me via Hangouts, the message is shown in my inbox in the web interface, but NOT on my phone in GMail, nor in Talk on my phone. I therefore never find out about a message until I use the web interface, which I don't really do because I have GMail on my phone......
And yes google are terrible at sending clear messages.
Just look at yesterdays confusing discussion RE hangouts/gchat/gtalk/google voice.
No idea what is going on there.