[Openbts-discuss] error with OpenBTSCLI

[北航 栾. <132...@16...>]

hi,
there is an error with my openbts-5.0. When I try  "sudo /OpenBTS/OpenBTSCLI" ,it always shows：

OpenBTS Command Line Interface (CLI) utility
Copyright 2012, 2013, 2014 Range Networks, Inc.
Licensed under GPLv2.
Includes libreadline, GPLv2.
Connecting to 127.0.0.1:49300...
connect stream socket: Connection refused
Is OpenBTS running?

but I have started the openbts!  sometimes I get it ,but whatever command line I try with "OpenBTS>",it come back to the previous state :~$   
my hardware is usrp n210 with an rfx daughterboard .I wonder if my installation has a problem,so please help me .thanks.
eric smith