date formatting

hello, in my template I have an input field which contains the date a shelf expires. <input type="text" name="{$shelf_expire.name}" value="{$shelf_expire_value}" class="bg{$shelf_expire.farbe}" size="{$shelf_expire.breite}" {$shelf_expire.readstatus} /> Given the value for $shelf_expire_value is 2099-12-31 the template returns just that. If I use: value="{$shelf_expire_value|date_format:'%d.%m.%Y'}" instead of value="{$shelf_expire_value}" I get the result: 04.10.2007, which is today's date... Is date_format only working with a certain type (format) of string? How can I get the desired output of: 31.12.2099? Thanks in advance, Peggy