c# - Specific runtime environment commands doesn't work in SSH.NET -

i'm using ssh.net connect (with username + password) server , run commands. connection server made manage components via cisco application control software, shouldn't matter because command sent are.

connection server works well, other commands work 2 specific commands doesn't work, , can't seem understand why.
commands fail are: changeto production , terminal length 0.
code pretty simple (simplified question, same flow):

using (var client = new sshclient(serverip, port, username, password) {     client.connect();     var cmd = client.runcommand("terminal length 0");     cmd = client.runcommand("changeto production");     // other command follow } 

while running same commands via putty works, , no, changeto shouldn't change to.
think problem here changing scopes (changeto production) via code, can't understand why.

any appreciated.

after searching , asking on codeplex forum of ssh.net library, understood problem: runcommand() function creates new shell every call.
new shell created default environment, , because terminal length 0 , changeto production change runtime-environment following commands, can't accomplished runcommand().
ended writing , reading directly shell stream (using sshclient.createshellstream()) , playing expect() , parse output need. way commands executed in same shell.