Name author changes from admin to other user

Hi,

I have a few wordpressblogs where I am the administrator and where are more subscribers with roles as author, editor and contributor (if that are the english words, I have the dutch version installed).
But when I write a post as Admin, the name of the author changes to the first name in the list of other writers. The name Admin is not in the list of authors. This is the problem at at least two different blogs. At the bottom of the editor there is a possibility to change the name of the author – Admin is not on that list. So I have the right to write and publish a post logged in as Admin, no problem, but it will be written in name of one of the other writers. Is this a common problem. Do I have to subscribe twice, once as admin and once as writer to write posts with my own name? I think it is something of 2.7, since I can’t remember having this problem before.

Karin