Why do you need them to acknowledge you were right?
I led way too many teams on live so I won't do it now, but in my experience, they learned a lesson that they will take to the next fight. Yeah, they neglected to give you a pat on the back for your foresight, but they still learned. Playing with PuGs, this is a common occurance. Human nature is such that we don't want to admit we may have possibly been slightly wrong even when the evidence is overwhelming. Give yourself your pat on the back and dont bother expecting it from them, you will just be disappointed most of the time. Don't give up trying to inform teammates of impending danger but try to be content with the fact that they did learn and will carry it forward, even if they don't acknowledge you for it.