date format error

[eluser]Mutsop[/eluser]
Hi,

I'm trying to format my date using the date_helper... But I do get an error for some reason.

A PHP Error was encountered
Severity: Notice
Message: A non well formed numeric value encountered
Filename: helpers/date_helper.php
Line Number: 94

Controller:

Code:

$data['datestring'] = "%Y-%m-%d";

View:

Code:

<?php echo mdate($datestring, $item->datum); ?>

Without using the date_helper I get this format:

2011-01-11 00:00:00