Try this:
"C:\Program Files\Teamspeak2_RC2\TeamSpeak.exe" 193.120.123.138:8787/nickname=(_|_)?loginname=(_|_)?password=(_|_)?channel=Private?channelpassword=(_|_)"
Obviously you replace the wee bums with your parameters.
Ensure the teamspeak directory is perfect, checking for spelling errors in case you renamed it or something...
There's a space between the "C:\Program Files\Teamspeak2_RC2\TeamSpeak.exe" and the IP starting and the '?' is the seperator for each parameter.
The parameters and stuff are in the helpfile, so all you have to do is RtFM...