I'm not real familiar with PerlApp, having read briefly about it and never used it. However, it seems you're using a tool called PerlSvc which bundles perl, some modules, and your original work into an executable file. The the PerlSvc.pm that you can't find in the file system is probably part of the bundle written inside the executable.

That bundle includes (probably also internally, although perhaps via the filesystem) Win32.pm to get some of its work done. The function it is counting on being available in Win32.pm is not available in the version it found to bundle into the executable. Win32 says that BuildNumber is only available in ActiveState's ActivePerl binary build. You must be using that version of the module in your bundling system in order to have that subroutine, it seems.

Check how PerlSvc and PerlApp in general are documented to use include paths and how their @INC is set up. Make sure the versions of any libraries you need for proper function are the versions those tools find first.