Voidswarth Won't Log Me In

Hey! So I'm new to Voidswrath, and I recently downloaded it to my Mac, I've downloaded and re downloaded and reinstalled everything twice including the Java Software that's required. Nothing. It won't let me log in! It only tells me I have invalid credentials! I've changed my Minecraft password and messaged Mojang themselves, but they said there is no fault with my account, and it logs in normally in minecraft and on the website!!

Help? Please? Thanks!