In addition to the comment about case-sensitivity, Perl looks for modules by walking down the @INC list, selecting (only) the first one that it finds.   There are several things which control the contents of this list, including:

• The use lib statement.
• The PERL5LIB environment variable.
• The initial list which is compiled-in to Perl.
• Manual manipulation of this (quite ordinary...) list variable.

When you install something ... and as usual, there are several ways to do it ... you need to control where the modules are installed, and then you need to be sure that these are on @INC at runtime.   It is, in fact, quite common to set up “custom” library-paths, e.g. to override the stock installations that might come with your system, or to give virtual-hosts their own predictable and unique environments that won’t change with their surroundings.