Gradle project sync failed

Hello, I tried to add the new dependency " compile 'com.android.support:recyclerview-v7:21.0.2' "but it caused the project sync to fail. I looked on google and it said try updating the compileSdkVersion to 21 buildToolsVersion to "21.0.1" which I did, but still no luck.

Here is my complete build.gradle code if it helps.

''' java

apply plugin: 'com.android.application'

android { compileSdkVersion 21 buildToolsVersion "21.0.1"

defaultConfig {
    applicationId "lmsankey.com.stormy_weather_app"
    minSdkVersion 14
    targetSdkVersion 21
    versionCode 1
    versionName "1.0"
}
buildTypes {
    release {
        runProguard false
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }
}

}

dependencies { compile fileTree(dir: 'libs', include: ['*.jar']) compile 'com.android.support:appcompat-v7:21.0.2' compile 'com.android.support:recyclerview-v7:21.0.2' compile 'com.squareup.okhttp:okhttp:2.2.0' compile 'com.jakewharton:butterknife:6.1.0'

}

'''

thanks