'Attach a file' don't work on YACS 7.4alpha16 [Integrated]

Because of problems with FCKEditor I installed YACS 7.4alpha16. It works fine but I can't attach a file. When I hit the link, the page can't be found.

I know that it is an alpha version, so I don't know this is the right place to post this message.

Rien Kok (Netherlands)