Error while accessing IMP

[pattar]

Hai,

I get this error when I try to access imp through

myhost/horde/ (or)
myhost/horde/imp


Fatal error: Failed opening required 'PEAR.php' (include_path='.:/usr/share/pear') in /var/

http://www/html/horde/lib/Registry.php

on line 13

The file PEAR.php is there in usr/share/pear.
I even tried adding a line nclude_path='.:/usr/share/pear', or prefixing it to PEAR.php.
Any idea why.

Thanks & Regards,
Srinivasan.