Module won't show up in “Edit Configuration”

Module not specified

使用android studio時，出現程序無法運行，手動添加run configuration時也無法找到module時
可以查看主程序的build.gradle
Make sure your build.gradle is

apply plugin: ‘com.android.application’
not

apply plugin: ‘com.android.library’
After you have changed, please sync your gradle again.

調查來源：
http://stackoverflow.com/questions/18368748/android-studio-module-wont-show-up-in-edit-configuration