I don't see a link to the manual but many of those optical to analog convertors are LIMITED in what optical audio will be converted. Most will not work if the output is 5.1. Look around for any other output options.
http://www.hdtvtest.co.uk/news/samsung-le32c450-le26c450-20101001847.htm and other places show a HEADPHONE jack which should be fine as it's analog and stereo.
I've got a Samsung LE32C450 LCD TV that I am trying to connect the optical out to a Goodmans surround sound system so that standard TV channels can be put through the surround sound.
The Surround sound only has Stereo Phono (RCA) connectors so I have connected the Optical link to an optical to RCA converter however when I try it out there is no sound out.
Can this be done? or am I missing something?