eclipse stp安装出错

eclipse  Ganymede Update Site中更新 SOA Development完成后，在SOA Tools 中新建SCA Component Project 报错：The selected wizard could not be started.
  Plug-in org.eclipse.stp.sc.sca.java was unable to load class   org.eclipse.stp.sc.sca.java.wizards.ScaJavaProjectWizard.
  org.eclipse.stp.sc.sca.java.wizards.ScaJavaProjectWizard不知道怎么回事，在线安装了好几次，都这样，请求帮助；