Recently, I made the mistake of wanting to use the Invasion mod with the Aether mod. Both require Forge 1.7.10. Here are the attempts I made to install Forge.
First, I tried to use MagicLauncher, as I usually do. I created a 1.7.10 configuration, put both the Aether mod and the Invasion mod in the .minecraft/mods folder, and loaded the universal version of Forge 1.7.10 into MagicLauncher along with Optifine 1.7.10. MagicLancher gives me nothing but OK messages. I start Minecraft, and not a single mod had been installed.
Next, I tried using the Forge launcher. I ran the launcher, placed the mods in the mods folder, opened Minecraft's normal launcher, and went to create a 1.7.10 Forge profile, but there was no 1.7.10 forge option when I tried to select a version. In confusion, I went into .minecraft/versions/1.7.10 Forge, only to find that there was no .jar file. The only file in the folder was the .json file. It appeared that the launcher had not actually installed a .jar file. It seems to me like the 1.7.10 Forge installer is actually defective.
So I ask you this: how do you expect Minecraft to run without a .jar file? Why didn't the launcher install a .jar file in the first place? Is the lack of a .jar file even the problem?