Gradle cannot resolve external dependencies

For some unknown reason, Gradle refuses to download every dependency that I put in the gradle.build file. I'm trying to get the dependency "me.dm7.barcodescanner: zbar: 1.7" but every time I try to sync my Gradle it just throws the following error:

Error:(6, 13) Failed to resolve: me.dm7.barcodescanner:zbar:1.7

      

        
        
        
      

    

It is not only zbar library, but every library, it is not com.android library. I'm not offline, so that's not the case either. Is there something wrong in my .build file?

apply plugin: 'com.android.application'

dependencies {
compile fileTree(include: '*.jar', dir: 'libs')
compile project(':MetaioSDK')
compile 'com.android.support:support-v4:22.0.0'
compile 'me.dm7.barcodescanner:zbar:1.7'
}

android {
    compileSdkVersion 19
    buildToolsVersion "21.1.0"

sourceSets {
    main {
        manifest.srcFile 'AndroidManifest.xml'
        java.srcDirs = ['src']
        resources.srcDirs = ['src']
        aidl.srcDirs = ['src']
        renderscript.srcDirs = ['src']
        res.srcDirs = ['res']
        assets.srcDirs = ['../../templatesContent_crossplatform']
    }

    // Move the tests to tests/java, tests/res, etc...
    instrumentTest.setRoot('tests')

    // Move the build types to build-types/<type>
    // For instance, build-types/debug/java, build-types/debug/AndroidManifest.xml, ...
    // This moves them out of them default location under src/<type>/... which would
    // conflict with src/ being used by the main source set.
    // Adding new build types or product flavors should be accompanied
    // by a similar customization.
    debug.setRoot('build-types/debug')
    release.setRoot('build-types/release')
}

      

        
        
        
      

    

}

buildscript {
    repositories {
        mavenCentral()
    }
dependencies {
    classpath 'com.android.tools.build:gradle:1.1.0'
    }
}