My b2evolution Version: 2.4.x

I got 403 error for a link that redirect to a b2evo blog.
Source: http://e.joucla.free.fr/
Destination: http://www.seven-passion.com/

I turn Debug ON and b2evolution think that the URL http://e.joucla.free.fr/ is invalid ("does not match url pattern!").
Do you know why ? How can I correct the problem ? (I want to keep the option "block referer spam on")

403 Forbidden
Please stop referer spam.

We have identified that you have been refered here by a known or supposed spammer.

If you feel this is an error, please bypass this message and leave us a comment about the error. We are sorry for the inconvenience.
[...]
Debug info
Debug messages
error | hit | memory | settings | timer | vars
error:
URL «http://e.joucla.free.fr/» does not match url pattern!
hit:
detect_referer(): Invalid URL format (http://e.joucla.free.fr/). (SPAM)
memory:
Len of serialized $cache_imgsize: 2
Len of serialized $cache_File: 2
settings:
GeneralSettings::get( db_version// ): '9700'
GeneralSettings::get( time_difference// ): [DEFAULT]: '0'
GeneralSettings::get( antispam_block_spam_referers// ): '1'
timer:
Starting timer total
Starting timer _main.inc
Starting timer sql_queries
Starting timer abstractsettings_GeneralSettings_get
vars:
Getting ReqURI from REQUEST_URI
$ReqHost: http://www.seven-passion.com
$ReqURI: /
$ReqPath: /