So it downloads fine, loads... and then just closes. Doesn't crash, just closes. At first I thought it was still loading but no, it just closes every time. I think the problem is that the modpack.jar isn't the right version, could that be the problem? Check it out for yourself, heres the modpack link- http://www.technicpack.net/modpack/details/acronia.371115 <<<< visit the link.
Thanks bros