Why do I get "issuer is not trusted" when I try to login to Subversion from Perl?

Question

I'm trying to log in to the subversion, I have stored permanently the certificate, but I keep getting this error:

RA layer request failed: PROPFIND request failed on '/svn/QFlife/Projects%20DotNet/QFX/trunk/Clients': PROPFIND of '/svn/QFlife/Projects%20DotNet/QFX/trunk/Clients': Server certificate verification failed: issuer is not trusted (https://vc.flife.de) at list.pl l

This is the code, that is responsible for auth:

sub getauth
{
    my $cred = shift;
    $cred->username($user);
    $cred->password($passwd);
}


my $ctx = SVN::Client->new
(
    auth =>     [    SVN::Client::get_simple_provider(),
                SVN::Client::get_simple_prompt_provider
                (
                    \&getauth,2
                ),
                SVN::Client::get_username_provider()
            ],
);

Could someone give me a clue what am I doing wrong?