The Unable install webchat

I download the webchat from’s official website,when i install error

exception

org.apache.jasper.JasperException: An exception occurred processing JSP page /setup-index.jsp at line 47
 44:         }
 45:         catch (XMPPException xe) {
 46:             // If anonymous login disabled.
 47:             if (xe.getXMPPError().getCode() == 403) {
 48:                 errors.put("connect", "Anonymous login test failed. Ensure that anonymous logins are enabled on the server.");
 49:             }
 50:             else {
      Stacktrace:     
           org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:505)     
           org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:416)     
           org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)     
           org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)     
           javax.servlet.http.HttpServlet.service(HttpServlet.java:717)     
           org.jivesoftware.webchat.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:45)     
           org.jivesoftware.webchat.SetupFilter.doFilter(SetupFilter.java:92)

root cause

java.lang.NullPointerException     
           org.apache.jsp.setup_002dindex_jsp._jspService(setup_002dindex_jsp.java:93)     
           org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)     
           javax.servlet.http.HttpServlet.service(HttpServlet.java:717)     
           org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)     
           org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)     
           org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)     
           javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
           org.jivesoftware.webchat.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:45)     
           org.jivesoftware.webchat.SetupFilter.doFilter(SetupFilter.java:92)

help me please