headset with mic racing online

[IROCK 030804]

i have a nice turtle beach headset with mic and can't figure out how to get the mic to work when racing online mutiplayer. the sound and spotter works great but no mic so i can talk with the people i'm racing with. can someone tell me how to fix this issue please? i'm sure there's probably something in my settings for this but i haven't figured it out yet. desperate to know how to fix this :-) thank you

[RaZoR-9]

no/none
there is no online voice =NascarHeat 1.2,3.4 - Nascar14/15 had it
we all join a Discord channel for chat