problem width exclamation mark in url

[eluser]Unknown[/eluser]
hello,

i'm using for example an url like this:
http://dev.netcodev.de/snacktv/videos/se...decken+auf!

generate with:
$title = 'Akte - Reportder decken auf!';
$url = site_url().'videos/sendung/'.urlencode(htmlentities($title,ENT_QUOTES,"UTF-8"));

ci take out following message:
Disallowed Key Characters videos/sendung/Akte_-_Reportder_decken_auf!

what can i do!