Fatal error: Unkown memberID

Information:

error message: Unkown memberID
error code: 0
file: /home/bigpoint3/include/lib/data/member/Member.class.php (47)
php version: 5.2.0-8+etch7
date: Wed, 20 Aug 2008 11:43:49 +0200
request: /blog/2753/
referer:
server: 10.32.7.13

Stacktrace:

#0 /home/bigpoint3/include/lib/data/member/MemberProfile.class.php(25): Member->__construct(NULL)
#1 /home/bigpoint3/include/lib/data/blog/Blog.class.php(87): MemberProfile->__construct(NULL)
#2 /home/bigpoint3/actions/action_blogDetail.es(77): Blog->getWriter()
#3 /home/bigpoint3/include/lib/system/template/Template.class.php(438): require('/home/bigpoint3...')
#4 /home/bigpoint3/include/lib/system/router/Router.class.php(174): Template->doAction('blogDetail')
#5 /home/bigpoint3/www/index.es(24): Router->handleExternal()
#6 {main}