Unable to resolve configuration with default name not found

I am trying to add a library project but I am unable to configure it. I get the message Configuration name with default not found.

Here is my build.gradle for app apply plugin: ‘com.android.application’

android {
    compileSdkVersion 21
    buildToolsVersion "21.0.2"
      defaultConfig {
        applicationId "com.example.sampleapplication"
        minSdkVersion 11
        targetSdkVersion 21
        versionCode 1
        versionName "1.0"
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
  dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:21.0.+'
    compile project(':libraries:PagerSlidingTabStrip')

Following is my settings.gradle

include ':app'
include ':libraries:PagerSlidingTabStrip'

Following is my folder structure: SampleApplication -.idea -app -build -gradle -libraries


Please help me.