Web servers often run in a different environment than the command-line.

What I would suggest, since you seem to have Data::Dumper loading fine, is to dump out %ENV and @INC, and compare the results in the web server to your command-line. Look for environment variables that affect the path, such as PATH, PERLLIB/PERL5LIB, etc. You may want to update the web server configuration to set them differently. There are other ways to set paths depending on the web framework you are using. It's also possible for the web server to use an entirely different version of Perl than the command-line, so you might want to check for that too.