So i just recently created a custom modpack based off of a guide. As far as i know i did everything correct, but, when i try to launch the modpack the technic launcher goes away, and then pops back up a couple of seconds later without even starting minecraft.
modpack: https://www.technicpack.net/modpack/who-wheres-short-shorts.1417280
just ignore all the stupid shit, its for a bunch of friends