Not sure what I did, but I had to reinstall Windows 7 (64bits). Now I installed the lastest version of Action! and the latest of Ventrilo (64bits), and Action! won't record anyone talking on vent.
Would I need Ventrilo 32bits? What could it be?
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Nah, just tried the 32bits client of Vent, Action! still not recording it.
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Ok FOUND IT! It's just a matter of toggling ON "Allow multi-channel audio recording". Simple.