"make install" fails

[E Kogler]

I want to install dovecot 2.2.25 on my opensuse 12.3 (yes, I know that this is an old distro).
"./configure, make" run with no problems but "make install" fails with:
[...]
libtool: warning: 'libstats_auth.la' has not been installed in '/usr/local/lib/dovecot/stats'
libtool: install: /usr/bin/install -c .libs/auth /usr/local/lib/dovecot/auth
libtool: install: /usr/bin/install -c .libs/checkpassword-reply /usr/local/lib/dovecot/checkpassword-reply
 /usr/bin/mkdir -p '/usr/local/lib/dovecot/auth'
/usr/bin/mkdir: can't create „/usr/local/lib/dovecot/auth“ : file exists
make[3]: *** [install-auth_moduleLTLIBRARIES] Fehler 1
make[3]: Leaving directory `/root/dovecot-2.2.25/src/auth'
make[2]: *** [install-am] Fehler 2
make[2]: Leaving directory `/root/dovecot-2.2.25/src/auth'
make[1]: *** [install-recursive] Fehler 1
make[1]: Leaving directory `/root/dovecot-2.2.25/src'
make: *** [install-recursive] Fehler 1
------------------------
I'm stuck.Can anyone help ?
Edgar