我正在尝试使用NetBeans IDE创建Flex应用程序，但是我有一个错误
Adobe Flex Compiler (mxmlc)
Version 4.5.0 build 20967
Copyright (c) 2004-2011 Adobe Systems, Inc. All rights reserved.
/opt/flex/frameworks/flex-config.xml(416): Error: unable to open 'libs/mx/mx.swc'
/home/a9un9hari/NetBeansProjects/Belajar/build.xml:82: The following error occurred while executing this line:
/home/a9un9hari/NetBeansProjects/Belajar/build.xml:179: exec returned: 1
BUILD FAILED (total time: 1 second)
我的弹性配置有什么问题？