Have you already checked (through netstat or similar) that the configured ports were not bound before launching the Server?

It could be a system-level limitation.
For instance, in unix/linux a user other than root cannot open a port lower than 1024 in listening.
Your case is worse, as you could not open even higher ports.
Lightstreamer opens the configured ports for listening in a standard way,
so, it should not suffer from limitations that don't apply also to other programs.