Android Studio 1.0.2 new project - Cannot resolve symbol 'ActionBarActivity'

I’m very confused. Today I just reinstalled Android Studio Version 1.0.2 (and the Android SDK) because I had some problems yesterday when I created a new project. I hoped that I could solve them by just reinstall everything, but actually the problem still exists and I don’t know how to solve it. After I created a new project in Android Studio and switch to my MainActivity (I didn't changed anything in one of the files), I always get the following errors displayed in the file. MainActivity.class: ``` package com.android.testapplication; import android.support.v7.app.ActionBarActivity; import android.os.Bundle; import android.view.Menu; import android.view.MenuItem; public class MainActivity extends ActionBarActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.menu_main, menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { // Handle action bar item clicks here. The action bar will // automatically handle clicks on the Home/Up button, so long // as you specify a parent activity in AndroidManifest.xml. int id = item.getItemId(); //noinspection SimplifiableIfStatement if (id == R.id.action_settings) { return true; } return super.onOptionsItemSelected(item); } } ``` Errors: - Cannot resolve symbol 'ActionBarActivity' - Cannot resolve method 'onCreate(android.os.Bundle)' - Cannot resolve method 'setContentView(int)' - Cannot resolve method 'getMenuInflater()' - Cannot resolve method 'setContentView(int)' - Cannot resolve method 'onOptionsItemSelected(android.view.MenuItem)' Project: build.gradle ``` buildscript { repositories { jcenter() } dependencies { classpath 'com.android.tools.build:gradle:1.0.0' // NOTE: Do not place your application dependencies here; they belong // in the individual module build.gradle files } } allprojects { repositories { jcenter() } } ``` Module: build.gradle ``` android { compileSdkVersion 21 buildToolsVersion "21.1.2" defaultConfig { applicationId "com.android.testapplication" minSdkVersion 14 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-v7:21.0.3' } ``` I already rebuild and cleaned my project and `'Sync Project with Gradle Files'` but none of them fixed my issues. The funny thing is, that I can compile and run my project on my smartphone… PS: I guess it seems to be a gradle issue, because whenever I add a new library such as `'com.google.android.gms:play-services:6.5.87'` and then try to import it `'import com.google.android.gms.gcm.GoogleCloudMessaging;'`. I also get the `'Cannot resolve symbol…'` error displayed. I didn’t complied it with the GCM Service… Thanks for your help in advance :)