[horde] fatal error of HORDE with LAMPP (Apache2 + PHP4)

["Markus K. Schäffauer"]

Hi,

after using HORDE successfully with the the preconfigured Apache / PHP 
of the SuSE 8.0 distribution, I tried to upgrade to Apache 2 using a 
LAMPP-Server with the following components:

    * Apache 2.0.44 <http://httpd.apache.org>
    * MySQL 3.23.55 <http://www.mysql.org>
    * PHP 4.3.0 <http://www.php.net>
    * Perl 5.8.0 <http://www.cpan.org/>
    * ProFTPD 1.2.7 <http://www.proftpd.org/>
    * phpMyAdmin 2.3.2 <http://www.phpwizard.net/projects/phpMyAdmin/>
    * OpenSSL 0.9.6h <http://www.openssl.org>
    * Freetype2 2.1.0 <http://www.freetype.org>
    * libjpeg 6b <http://www.ijg.org/>
    * libpng 1.2.2 <http://www.libpng.org/>
    * gdbm 1.8.0 <http://www.gnu.org/software/gdbm/gdbm.html>
    * zlib 1.1.4 <http://www.gzip.org/zlib/>
    * expat 1.2 <http://www.jclark.com/xml/expat.html>
    * ming 0.2a <http://ming.sourceforge.net/>
    * Sablotron 0.96 <http://www.gingerall.com/>
    * libxml 2.4.26 <http://xmlsoft.org/>
    * Webalizer 2.01 <http://www.mrunix.net/webalizer/>
    * pdf class 009c <http://www.ros.co.nz/pdf/>
    * ncurses 5.2 <http://www.gnu.org/software/ncurses/>

(cf. LAMPP = www.apachefriends.org). The LAMPP status is giving the 
result that my installation of LAMPP is ok.
I copied the well functioning archives ../horde and ../mysql of the 
former installation to the corresponding /opt/lampp/.. archives.
I managed to open the copied mysql-database HORDE with the 
phpMyAdmin-tool of the new LAMPP-server and verified that everything is ok.
But when I try to open http://server/horde, instead of the initial page 
I get the following error message:

    Fatal error: Call to undefined function: _() in 
/opt/lampp/htdocs/horde/config/registry.php on line 67

What is going wrong?
I heard that Apache 2 has problems with interpreting some commands of 
PHP4. May be this is the reason?
Is there any solution to this problem?

Thank you very much,
Markus Schäffauer