internal server error in using HTML5 VPN portal

i have a problem with the HTML5 VPN portal.

it shows internal server error when connect to the instance,

while RDP is working well when directly logon to it.

below is the error log,anyone an idea?thank u.

2015:12:17-16:55:40 sopras01 screenmgr[4130]: >=========================================================================
2015:12:17-16:55:40 sopras01 screenmgr[4130]: Unhandled exception below on_data(): AnyEvent::Handle: either an existing fh or the connect parameter must be specified at /</usr/sbin/screenmgr.plx>AnyEvent/Subprocess/Job/Delegate/Handle.pm line 70
2015:12:17-16:55:40 sopras01 screenmgr[4130]:
2015:12:17-16:55:40 sopras01 screenmgr[4130]: 1. (eval):135() /</usr/sbin/screenmgr.plx>Core/Log.pm
2015:12:17-16:55:40 sopras01 screenmgr[4130]: 2. Core::Log::log:134() /</usr/sbin/screenmgr.plx>Core/Log.pm
2015:12:17-16:55:40 sopras01 screenmgr[4130]: 3. Core::Log::crit:170() /</usr/sbin/screenmgr.plx>Core/Log.pm
2015:12:17-16:55:40 sopras01 screenmgr[4130]: 4. CLV::WebsocketServer::on_data:135() /</usr/sbin/screenmgr.plx>CLV/WebsocketServer.pm
2015:12:17-16:55:40 sopras01 screenmgr[4130]: 5. CLV::WebsocketServer::__ANON__:144() /</usr/sbin/screenmgr.plx>CLV/WebsocketServer.pm
2015:12:17-16:55:40 sopras01 screenmgr[4130]: 6. AnyEvent::Handle::__ANON__:1695() /</usr/sbin/screenmgr.plx>AnyEvent/Handle.pm
2015:12:17-16:55:40 sopras01 screenmgr[4130]: 7. AnyEvent::Handle::_drain_rbuf:1270() /</usr/sbin/screenmgr.plx>AnyEvent/Handle.pm
2015:12:17-16:55:40 sopras01 screenmgr[4130]: 8. AnyEvent::Handle::__ANON__:1923() /</usr/sbin/screenmgr.plx>AnyEvent/Handle.pm
2015:12:17-16:55:40 sopras01 screenmgr[4130]: 9. AnyEvent::Strict::__ANON__:44() /</usr/sbin/screenmgr.plx>AnyEvent/Strict.pm
2015:12:17-16:55:40 sopras01 screenmgr[4130]: 10. (eval):222() screenmgr.pl
2015:12:17-16:55:40 sopras01 screenmgr[4130]: 11. main::top-level:222() screenmgr.pl
2015:12:17-16:55:43 sopras01 screenmgr[4130]: <=========================================================================
2015:12:17-16:55:43 sopras01 screenmgr[4130]: Client 1142: disconnected: Broken pipe
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