IsomorphicSMP

Ok, the link for my modpack is; https://www.dropbox.com/s/xtxrggszmeq5gox/modpack.zip?dl=1

So I have my modpack in the launcher, and it installs just fine, no errors at all. But when me, or anyone else clicks play, it loads, the launcher disappears, then the launcher just comes back and nothing happens, once again it displays no errors. Can anyone help me with this? Thanks!