Perl Script can't load LDAP.pm

hi,
a perl script for a login runs on a normal windows account.
i want it to run automatically, so now it runs as windows service from the system user.
but on system user the script doesn't work, unlike on normaler user, and throws this error message:

Can't load 'path.../SSLeay.dll' for module Net::SSLeay: load_file: The specified module could not be found at path.../Dynaloader.pm line 200, <DATA> line 522. at path.../ SSL.pm line 18
Compilation failed in require at directory.../SSL.pm line 18, <DATA> line 522.
BEGIN failed--compilation aborted at path.../SSL.pm line 18, <DATA> line 522.
Compilation failed in require at path.../LDAP.pm line 105, <DATA> line 522.

what does this mean?
why the script works from normal user account and not as service from windows system user ?

any clue is wellcome, thanks