You should always run the installer, rather than just copying files over. The installer may compile parts of itself (anything with .xs files), configure other things (like setting up libnet.cfg, for Bundle::libnet, or add more than just perl modules (LWP has a few executables to call it from the command line).

Most important, however, is the results of 'make test', which will help you to pinpoint where there are going to be problems.

Most likely, it's just a matter of the LWP files not being in the right place for perl to find ... if it's not in the same place as where you placed SOAP::Lite, you may need to do a 'use lib' to tell perl where to look for the other modules.