I think that you already have the explanation: "as soon as"
It seems that we can't modify our "old" posts. ;)
Help > Posting: "It is up to your forum's administrator to set the permissions that determine who will be allowed to Modify and Delete posts, and for how long after making the original post"
If you are referring to your [heberger-image.fr/data/images/16990_JSCH.jpg] signature, perhaps that you should complain against "heberger-image.fr" rather than "camcaps.net". 8)