A system error occurred

ognl.OgnlException: id [java.lang.NumberFormatException: For input string: "null"]
	at ognl.ObjectPropertyAccessor.setPossibleProperty(ObjectPropertyAccessor.java:83)
	at ognl.ObjectPropertyAccessor.setProperty(ObjectPropertyAccessor.java:131)
	at ognl.OgnlRuntime.setProperty(OgnlRuntime.java:1670)
	at ognl.ASTProperty.setValueBody(ASTProperty.java:101)
	at ognl.SimpleNode.evaluateSetValueBody(SimpleNode.java:177)
	at ognl.SimpleNode.setValue(SimpleNode.java:246)
	at ognl.Ognl.setValue(Ognl.java:476)
	at net.sf.click.util.PropertyUtils.setValueOgnl(PropertyUtils.java:169)
	at net.sf.click.ClickServlet.processPageRequestParams(ClickServlet.java:1111)
	at net.sf.click.ClickServlet.initPage(ClickServlet.java:1056)
	at net.sf.click.ClickServlet.createPage(ClickServlet.java:877)
	at net.sf.click.ClickServlet.handleRequest(ClickServlet.java:345)
	at net.sf.click.ClickServlet.doGet(ClickServlet.java:284)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:104)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:45)
	at winstone.ServletConfiguration.execute(ServletConfiguration.java:249)
	at winstone.RequestDispatcher.forward(RequestDispatcher.java:335)
	at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:378)
	at marubinotto.util.web.CustomizedSecurityFilter.doFilter(CustomizedSecurityFilter.java:29)
	at winstone.FilterConfiguration.execute(FilterConfiguration.java:195)
	at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:368)
	at winstone.RequestDispatcher.forward(RequestDispatcher.java:333)
	at winstone.RequestHandlerThread.processRequest(RequestHandlerThread.java:244)
	at winstone.RequestHandlerThread.run(RequestHandlerThread.java:150)
	at java.lang.Thread.run(Thread.java:750)
/-- Encapsulated exception ------------\
java.lang.NumberFormatException: For input string: "null"
	at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
	at java.lang.Long.parseLong(Long.java:589)
	at java.lang.Long.parseLong(Long.java:631)
	at ognl.OgnlOps.longValue(OgnlOps.java:191)
	at net.sf.click.util.RequestTypeConverter.convertValue(RequestTypeConverter.java:112)
	at net.sf.click.util.RequestTypeConverter.convertValue(RequestTypeConverter.java:63)
	at ognl.OgnlRuntime.getConvertedType(OgnlRuntime.java:701)
	at ognl.OgnlRuntime.setFieldValue(OgnlRuntime.java:1153)
	at ognl.ObjectPropertyAccessor.setPossibleProperty(ObjectPropertyAccessor.java:76)
	at ognl.ObjectPropertyAccessor.setProperty(ObjectPropertyAccessor.java:131)
	at ognl.OgnlRuntime.setProperty(OgnlRuntime.java:1670)
	at ognl.ASTProperty.setValueBody(ASTProperty.java:101)
	at ognl.SimpleNode.evaluateSetValueBody(SimpleNode.java:177)
	at ognl.SimpleNode.setValue(SimpleNode.java:246)
	at ognl.Ognl.setValue(Ognl.java:476)
	at net.sf.click.util.PropertyUtils.setValueOgnl(PropertyUtils.java:169)
	at net.sf.click.ClickServlet.processPageRequestParams(ClickServlet.java:1111)
	at net.sf.click.ClickServlet.initPage(ClickServlet.java:1056)
	at net.sf.click.ClickServlet.createPage(ClickServlet.java:877)
	at net.sf.click.ClickServlet.handleRequest(ClickServlet.java:345)
	at net.sf.click.ClickServlet.doGet(ClickServlet.java:284)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:104)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:45)
	at winstone.ServletConfiguration.execute(ServletConfiguration.java:249)
	at winstone.RequestDispatcher.forward(RequestDispatcher.java:335)
	at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:378)
	at marubinotto.util.web.CustomizedSecurityFilter.doFilter(CustomizedSecurityFilter.java:29)
	at winstone.FilterConfiguration.execute(FilterConfiguration.java:195)
	at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:368)
	at winstone.RequestDispatcher.forward(RequestDispatcher.java:333)
	at winstone.RequestHandlerThread.processRequest(RequestHandlerThread.java:244)
	at winstone.RequestHandlerThread.run(RequestHandlerThread.java:150)
	at java.lang.Thread.run(Thread.java:750)
\--------------------------------------/