Couple of points no one's mentioned yet: all lower case module names are reserved for use as Perl pragma (e.g. strict, warnings). Avoid using them and instead Capitalize the first letter of your modules.

Which leads to the next point: Perl comes with a blib pragma that's used for loading an uninstalled module during installation and testing. It's possible that any strange behavior you're seeing (just speculating since the original problem doesn't mention this, but I'm getting a hint of XY problem none the less) is because you're picking up Perl's blib not your blib.pm. Proper module naming would avoid potential problems such as this.

Update: Very valid point from the Anonomunk below. If you're not sure one can always check perlmodlib for a list.