加载applet时出现空指针异常

Question

错误：

java.lang.NullPointerException
 at sun.plugin2.applet.JNLP2Manager.getAppInfo(Unknown Source)
 at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
 at java.lang.Thread.run(Unknown Source) 

<script src="http://java.com/js/deployJava.js"></script>  
    <script>  
        var attributes = {  
            code:       "com.futronictech.ScanDemoJApplet.class",  
            archive:    "FtrScanApplet.jar",  
            width:      400,  
            height:     500  
        };  
        var parameters = {jnlp_href:"launch.jnlp"};   
        var version = "1.6";   
       deployJava.runApplet(attributes, parameters, version);  
    </script>  
    <!-- Or use the following applet element to launch the applet using jnlp_href -->  
   <!--  <applet width="400" height="500">  
        <param name="jnlp_href" value="launch.jnlp"/>  
    </applet> -->  

我在应用程序根目录中添加了FtrScanApplet.jar。我已经更新了Java，改变了java的安全性并且还清除了缓存但没有结果。 请帮我解决这个问题。