gradle buid error :No such property: COMPILE_SDK for class: org.gradle.api.Project
<p>I added a gradle.properties in the project，the content like 
<a href="https://i.stack.imgur.com/U0G2Z.png" rel="nofollow">this</a></p>

<p>and this is my main gradle
<a href="https://i.stack.imgur.com/jH9X5.png" rel="nofollow">content</a></p>

<p>but it build error :<code>No such property: COMPILE_SDK for class: org.gradle.api.Project</code> .some body help me,thank you very much!</p>