500 Servlet Exception

[show] java.lang.StringIndexOutOfBoundsException: String index out of range: -1

java.lang.StringIndexOutOfBoundsException: String index out of range: -1
	at java.lang.String.substring(String.java:1931)
	at com.ss.server.share.CountryManager.getCountrystr(CountryManager.java:25)
	at _jsp._web_22dinf._jsp._schedule._pdfhelp__jsp._jspService(WEB-INF/jsp/schedule/../schedule/ihtml/schedule_pdf_form.ihtml:4)
	at _jsp._web_22dinf._jsp._schedule._pdfhelp__jsp._jspService(_pdfhelp__jsp.java:37)
	at com.caucho.jsp.JavaPage.service(JavaPage.java:64)
	at com.caucho.jsp.Page.pageservice(Page.java:548)
	at com.caucho.server.dispatch.PageFilterChain.doFilter(PageFilterChain.java:194)
	at com.caucho.server.webapp.DispatchFilterChain.doFilter(DispatchFilterChain.java:131)
	at com.caucho.server.dispatch.ServletInvocation.service(ServletInvocation.java:314)
	at com.caucho.server.webapp.RequestDispatcherImpl.include(RequestDispatcherImpl.java:440)
	at com.caucho.server.webapp.RequestDispatcherImpl.include(RequestDispatcherImpl.java:359)
	at com.caucho.jsp.PageContextImpl.include(PageContextImpl.java:1091)
	at _jsp._schedule._index__jsp._jspService(schedule/index.jsp:26)
	at _jsp._schedule._index__jsp._jspService(_index__jsp.java:30)
	at com.caucho.jsp.JavaPage.service(JavaPage.java:64)
	at com.caucho.jsp.Page.pageservice(Page.java:548)
	at com.caucho.server.dispatch.PageFilterChain.doFilter(PageFilterChain.java:194)
	at com.caucho.server.webapp.WebAppFilterChain.doFilter(WebAppFilterChain.java:156)
	at com.caucho.server.webapp.AccessLogFilterChain.doFilter(AccessLogFilterChain.java:95)
	at com.caucho.server.dispatch.ServletInvocation.service(ServletInvocation.java:314)
	at com.caucho.server.hmux.HmuxRequest.handleInvocation(HmuxRequest.java:480)
	at com.caucho.server.hmux.HmuxRequest.handleRequestImpl(HmuxRequest.java:374)
	at com.caucho.server.hmux.HmuxRequest.handleRequest(HmuxRequest.java:341)
	at com.caucho.network.listen.TcpSocketLink.dispatchRequest(TcpSocketLink.java:1395)
	at com.caucho.network.listen.TcpSocketLink.handleRequest(TcpSocketLink.java:1351)
	at com.caucho.network.listen.TcpSocketLink.handleRequestsImpl(TcpSocketLink.java:1335)
	at com.caucho.network.listen.TcpSocketLink.handleRequests(TcpSocketLink.java:1243)
	at com.caucho.network.listen.TcpSocketLink.handleAcceptTaskImpl(TcpSocketLink.java:1037)
	at com.caucho.network.listen.ConnectionTask.runThread(ConnectionTask.java:117)
	at com.caucho.network.listen.ConnectionTask.run(ConnectionTask.java:93)
	at com.caucho.network.listen.SocketLinkThreadLauncher.handleTasks(SocketLinkThreadLauncher.java:175)
	at com.caucho.network.listen.TcpSocketAcceptThread.run(TcpSocketAcceptThread.java:61)
	at com.caucho.env.thread2.ResinThread2.runTasks(ResinThread2.java:173)
	at com.caucho.env.thread2.ResinThread2.run(ResinThread2.java:118)