[horde] Horde Fatal error: Call to undefined function: raiseerror()

[hguo@ime.pku.edu.cn]

Hello all,

I just installed horde, but I encountered the following problem which really
bothers me. After configuring the horde and imp, I clicked the imp, but it
turned out the following error:

Fatal error: Call to undefined function: raiseerror() in
/home/httpd/html/horde/lib/Horde.php on line 1387

When I used the test.php, it told me that my PEAR is not recent, but actually,
my PHP is version 4.4, and my PEAR is version 1.4.6. I tried PHP 5.1.2, and
there was the same problem. Other sections of test seemed ok.

Anyone knows what's the problem? Any help is appreciated!

Hui Guo