[horde] error while wrong password on plesk 11.5 + mod_fcgid

[Nethub Online]

Hi all,

I tested on below environment which doesn't not cause any error.
Plesk 11.0.9
php 5.3.3
ionCube PHP Loader v4.0.14
Server API: Apache 2.0 Handler
Horde Version: 5.1.1
Imp [Mail]: H5 (6.1.2)

And I tested the old Horde bundled with Plesk 11.5.30, there is no error too.
Plesk 11.5.30
php 5.3.3
ionCube PHP Loader v4.2.2
Server API: CGI/FastCGI
Horde Version: 5.0.4 
Imp [Mail]: H5 (6.0.4)

However I tested on below environment, there is error while I entered wrong
password.
Plesk 11.5.30
php 5.3.3
Server API: CGI/FastCGI
ionCube PHP Loader v4.2.2
Horde Version: 5.1.1
Imp [Mail]: H5 (6.1.2)

Error: [Mon Jul 15 06:22:03 2013] [warn] [client 203.185.13.146] mod_fcgid:
stderr: PHP Fatal error:  Call to a member function write() on a non-object
in /usr/share/psa-pear/pear/php/Horde/Imap/Client/Socket.php on line 3912,
referer: http://webmail.plesktest3.demo360.net/login.php


The line 3912 is "$this->_connection->write($val->escape());" which is
related to function "protected function _processCmd($pipeline, $cmd,
$data)", I checked this function does not exist in the old Horde (pear)
bundled with Plesk 11.5.30


I don't know what further information is needed, can someone help on it?