I have been fiddling with the build.gradle, mcmod.info, and MANIFEST.MF files in my mod jar for a little while and it seems that nothing that I can type solves the problem. My mod is working perfectly in the eclipse debugger, however FML only loads the coremod and fails to load the normal FML mod when it is installed in the mods folder.

 

My Jar can be found here http://www.mediafire.com/download/56dzfxr2olgeo54/scoreboardmod-r1-1.8.jar

 

mcmod.info

[
{
  "modid": "scoreboardmod",
  "name": "Scoreboard Repositioning Mod Forge",
  "description": "A Mod That Can Move The Scoreboard!",
  "version": "r1-1.8",
  "mcversion": "1.8",
  "url": "",
  "updateUrl": "",
  "authorList": ["kirby2ig"],
  "credits": "",
  "logoFile": "",
  "screenshots": [],
  "dependencies": []
}
]

 

build.gradle

buildscript {
    repositories {
        mavenCentral()
        maven {
            name = "forge"
            url = "http://files.minecraftforge.net/maven"
        }
        maven {
            name = "sonatype"
            url = "https://oss.sonatype.org/content/repositories/snapshots/"
        }
    }
    dependencies {
        classpath 'net.minecraftforge.gradle:ForgeGradle:1.2-SNAPSHOT'
    }
}

apply plugin: 'forge'

version = "r1-1.8"
group= "me.kirby2ig.scoreboardmod" // http://maven.apache.org/guides/mini/guide-naming-conventions.html
archivesBaseName = "scoreboardmod"

minecraft {
    version = "1.8-11.14.1.1341"
    runDir = "eclipse"
    
    // the mappings can be changed at any time, and must be in the following format.
    // snapshot_YYYYMMDD   snapshot are built nightly.
    // stable_#            stables are built at the discretion of the MCP team.
    // Use non-default mappings at your own risk. they may not allways work.
    // simply re-run your setup task after changing the mappings to update your workspace.
    mappings = "snapshot_20141130"
}

jar {
    manifest {
        attributes 'FMLCorePlugin': 'me.kirby2ig.ScoreboardRepositionForge.ScoreboardRepositionForgeTweaker'
	attributes 'FMLCorePluginContainsMod': 'true'
    }
}

dependencies {
    // you may put jars on which you depend on in ./libs
    // or you may define them like so..
    //compile "some.group:artifact:version:classifier"
    //compile "some.group:artifact:version"
      
    // real examples
    //compile 'com.mod-buildcraft:buildcraft:6.0.8:dev'  // adds buildcraft to the dev env
    //compile 'com.googlecode.efficient-java-matrix-library:ejml:0.24' // adds ejml to the dev env

    // for more info...
    // http://www.gradle.org/docs/current/userguide/artifact_dependencies_tutorial.html
    // http://www.gradle.org/docs/current/userguide/dependency_management.html

}

processResources
{
    // this will ensure that this task is redone when the versions change.
    inputs.property "version", project.version
    inputs.property "mcversion", project.minecraft.version

    // replace stuff in mcmod.info, nothing else
    from(sourceSets.main.resources.srcDirs) {
        include 'mcmod.info'
                
        // replace version and mcversion
        expand 'version':project.version, 'mcversion':project.minecraft.version
    }
        
    // copy everything else, thats not the mcmod.info
    from(sourceSets.main.resources.srcDirs) {
        exclude 'mcmod.info'
    }
}

 

MANIFEST.MF

Manifest-Version: 1.0
FMLCorePlugin: me.kirby2ig.ScoreboardRepositionForge.ScoreboardRepositionForgeTweaker
FMLCorePluginContainsMod: true

 

I feel like I am just missing something that would be really easy to fix, but I can't find it.

 

EDIT: Also, Forge loads my mod just fine when I remove the FMLCorePlugin and FMLCorePluginContainsMod lines from my MANIFEST.MF.

Solved it myself. I changed

FMLCorePluginContainsMod: true

to

FMLCorePluginContainsFMLMod: true

It did turn out to be a simple spelling mistake in the end.