[horde] function _() not found

[Oliver Schönrock]

Sorry but this is a really basic question I am sure 8-)

I have just built my first Linux server using RedHat 7.3. I am running 
Horde  quite successfully on a couple of virtual hosts and have even made a 
few mods of my own.

- Appache 1.3.23 installed and running ok, serving html fine
- PHP 4.2.2 compiled and installed as mod_php ok, apache now serving 
standard php pages ok
- install horde 2.1/ IMP3.1/ Turba 1.0 etc etc
- PEAR 4.1.0 downloaded from ftp.horde.org (long time ago) and unzipped 
into a pear directory under horde

I have
php_value include_path .:..:/var/www/html/horde/pear

in a .htaccess file under horde

when I hit the horde/index.php i get the following error:

Fatal error: Call to undefined function: _() in 
/var/www/html/horde/config/registry.php on line 67

now I don't even know what this function is 8-). I have noticed it all 
through the horde source for the sting literals and I assume it has 
something to do with localisation. Is it part of pear? I have looked all 
through the php.net docs the pear source and the horde source and can't 
find a definiton for _()...?

What module am I missing? The install is exactly the same as on my virtual 
hosts...??!!

Please help, confused!

Oliver