JavaFX 部署 运行出错?报错

刚学JavaFX 跟着教程 一步一步往下做, 到部署的时候
右键bulid.xml文件, Run as ==> Ant build 报错

谁知道可能是什么原因吗?

init-fx-tasks:
[taskdef] Could not load definitions from resource com/sun/javafx/tools/ant/antlib.xml. It could not be found.
do-deploy:
[copy] Copying 3 files to D:\MyWork\git\git-demo\pack_fx\build\dist\libs

BUILD FAILED
D:\MyWork\git\git-demo\pack_fx\build\build.xml:116: Problem: failed to create task or type javafx:com.sun.javafx.tools.ant:resources
Cause: The name is undefined.
Action: Check the spelling.
Action: Check that any custom tasks/types have been declared.
Action: Check that any / declarations have taken place.
No types or tasks have been defined in this namespace yet