gradle, could not find property in buildSrc

I made custom task, name MySqlTask.groovy ``` import org.gradle.api.DefaultTask import org.gradle.api.tasks.TaskAction public class MySqlTask extends DefaultTask { def hostname = 'localhost' def sql @TaskAction def runQuery() { //to do something... } } ``` And, I put this file in rootProject/buildSrc/src/main/groovy. My build file is customtasksourcetree.gradle. task createDatabase(type: MySqlTask) { sql = 'CREATE DATABASE IF NOT EXISTS example' } When I run gradle with customtasksrc.gradle then raise error like this. ``` FAILURE: Build failed with an exception. * Where: Build file '/Users/need4spd/Programming/Java/workspace/gradleTest/customtasksourcetree.gradle' line: 1 * What went wrong: A problem occurred evaluating root project 'gradleTest'. > Could not find property 'MySqlTask' on root project 'gradleTest'. ``` I have read that, my custom task file in buildSrc will compiled and add to classpath during build time automatically. I can see compiled MySqlTask.class in buildSrc/build/classes. What's the problem? Thanks.