Blargh.
You know, I had just washed all the rot-gut down the drain when I came across this.
"latest perl and freeTDS" mean absolutely nothing, what versions are you using for freeTDS? I can see you're using perl 5.6.1 -- but did you have problems compiling freeTDS? Or are you using a binary? if so, what happens when you try to compile it?

My particular version of this story ended with us purchasing an NT license because the sybase drivers are free on win32 systems, and a fraction of the cost of Solaris drivers. We attempted to compile and troubleshoot freeTDS for a week before we cried uncle... :(
Good luck, but I've seen a whole lotta people who've not been able to use freeTDS at *all*, let alone with DBD::Sybase.
Does anyone have any positive reviews? anyone?