modify userPassword via perl-ldap?

Hello,

I'm trying to modify the userPassword value from within a perl script
using Perl::LDAP.
I generate an encrypted pwd in perl and then write it to FedoraDS via
ldap->modify
The update seems successfull but when I query FedoraDS afterwards the
string in userPassword is not the same as the one I generated. What
exactly is happening in the background giving this result? I tried
writing the same value to another attribute (eg mail) and then it is
as expected.
What's the best way to update the userPassword from within perl?

Thanks again,
Jo