[Custom Modpack Launching As Vanilla]

I've been working on a mudpack with some friends, in hopes of eventually running a server. So far, we've been able to solve most of our own problems concerning the modpack itself, but I just attempted to update the forge version inside the pack, and now it loads in as vanilla Minecraft. 

Modpack

Log was very short, so I figured I'd paste it here. In all honesty, I may be looking at the wrong things.

[02:26:30] [Client thread/INFO]: Setting user: Tosiv
[02:26:32] [Client thread/WARN]: Skipping bad option: lastServer:
[02:26:32] [Client thread/INFO]: LWJGL Version: 2.9.4
[02:26:33] [Client thread/INFO]: Reloading ResourceManager: Default
[02:26:46] [Sound Library Loader/INFO]: Starting up SoundSystem...
[02:26:46] [Thread-3/INFO]: Initializing LWJGL OpenAL
[02:26:46] [Thread-3/INFO]: (The LWJGL binding of OpenAL.  For more information, see http://www.lwjgl.org)
[02:26:47] [Thread-3/INFO]: OpenAL initialized.
[02:26:47] [Sound Library Loader/INFO]: Sound engine started
[02:26:50] [Client thread/INFO]: Created: 1024x512 textures-atlas
[02:26:51] [Client thread/INFO]: Narrator library for x64 successfully loaded
[02:26:54] [Client thread/INFO]: Stopping!
[02:26:54] [Client thread/INFO]: SoundSystem shutting down...
[02:26:54] [Client thread/WARN]: Author: Paul Lamb, www.paulscode.com
 

Launcher Bug

This has happened every time I tried opening it. 

Steps to reproduce? Download and launch modpack.

Expected versus observed? mods load versus vanilla Minecraft is launched

Attempted fixes so far: deleted version json file. Deleted and reinstalled pack. 

Even pointing me in the right direction would be greatly appreciated, cheers. If I find it on my own, I'll reply and/or close the thread. Thanks.