Warning: pdo_dummy::rowCount() - php

Question

So i tried changing all my MySQL queries in order to use PDO..
After changing, I have some few errors like this..when trying to add a new comment in file.php, annoying thing is the comment is added but this error comes as well..
Warning: pdo_dummy::rowCount() Your last query was unsuccessful and returned FALSE
instead of a fetchable result. See pdo_error() to find out why. - caused by /home/user
/public_html/file.php, line 118, when calling pdo_affected_rows(); in /home/user
/public_html/includes/pdo_mysql.php on line 1068
On line 118 in file.php
if (pdo_affected_rows() == 1)
show_error_msg(T_("COMPLETED"), T_("COMMENT_ADDED"), 0);
else
show_error_msg(T_("ERROR"), T_("UNABLE_TO_ADD_COMMENT"), 0);
On Line 1068 in pdo_mysql.php
function pdo_trigger_error($msg, $level=E_USER_NOTICE) {
// locate source of last pdo_*() invocation
foreach ((debug_backtrace()) as $src) {
// skip any functions in the current file
if (empty($src["file"])) {
$src["file"] = "{main}";
$src["line"] = "-";
}
if ($src["file"] != __FILE__) {
$dir = dirname($src["file"]);
$file = basename($src["file"]);
$msg .= " - caused by $dir/<b>$file</b>, line <b>$src[line]</b>, when calling <a>$src[function]()</a>;";
break;
}
}
// pass on to actual error handler chain
trigger_error($msg, (($level == 1<<14) && (PHP_VERSION < 5.3)) ? E_USER_NOTICE : $level);
}
I'm thinking this error occurs as a result of conflict but not sure...
trigger_error($msg, (($level == 1<<14) && (PHP_VERSION < 5.3)) ? E_USER_NOTICE : $level);
The complete pdo_mysql.php script is here Using PDO_MySQL
Thanks.....