Error:Execution failed for task ':app:dexDebug'. > com.android.ide.common.internal.LoggedErrorException: Failed to run command:

this is my gradle file:- guy's please help me its very important for me to solve this error...

'android {
compileSdkVersion 23
buildToolsVersion "21.1.2"

defaultConfig {
    applicationId "com.example.samruddhi.myapplication"
    minSdkVersion 15
    targetSdkVersion 23
    versionCode 1
    versionName "1.0"
}
buildTypes {
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 
    }