I to am having the same problem, people say doing like http://beta.technicpack.net/api/modpack/m-cs-pack or like going to settings and checking always use beta modpacks, but nothing works, Not blaming the devs, im just saying they should make a new modpack launcher with no bugs/erros at all. If im correct Macs cant play added modpacks, so they should also make a new modpack launcher that supports all systems what so ever.
~TekkitLoverMichael2344