It looks like your PEAR path is not within the possible paths.
to try
$paths = explode(PATH_SEPARATOR,get_include_path());
$paths[] = '/path/to/pear';
$path_combined = implode(PATH_SEPARATOR,$paths);
set_include_path($path_combined);
ini_set('include_path',$path_combined);
then try loading the module, otherwise just add it to your php.ini and restart the server.
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