Bug:Task "not found in project ':app'"

when i build android code,

occur problem:

Error:FAILURE: Build failed with an exception.

• What went wrong:
  Task '' not found in project ':app'.

• Try:
  Run gradle tasks to get a list of available tasks. Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

apply plugin: 'com.android.application'

buildscript {
repositories {
mavenCentral()
}
dependencies {
classpath "com.android.tools.build:gradle:1.0.0"
}
}

android {
compileSdkVersion 19
buildToolsVersion '20.0.0'
defaultConfig {
applicationId 'com.jhp.sida'
minSdkVersion 14
targetSdkVersion 19
versionCode 1
versionName '1.0.0'
}
buildTypes {
release {
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
productFlavors {
}

lintOptions {
disable 'InvalidPackage'
}

packagingOptions {
exclude 'META-INF/services/javax.annotation.processing.Processor'
}
sourceSets {
main {
jniLibs.srcDirs = ['src/main/jniLibs']
}
}
}

dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
}

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please show your project struct and 'build.gradle' file

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已经解决
http://stackoverflow.com/questions/25172006/android-studio-build-fails...