Hi sebastiaopburnay
In addition to the above suggestions, you'll want to make sure that you're running with the same interpreter that your DBD::Sybase module is installed to. From a command prompt, type which perl and then compare it to what's on the first line of your script. If they don't match, you've got a problem. You could solve it by a) updating that first line to match the location that which perl spits out, b) change that first line to #! /usr/bin/env perl or c) invoke your script by using perl <script> [options].
