Agora puts a cookie on your machine noting which is the last post you have read. That is the post that gets responded to.

You are opening multiple posts at one time. Probably you have a dial-up phone connection, so while you wait for one post to be accessed you are opening other posts in additional windows or tabs. The end result is you have several posts open on your system at one time, but only one of them is the ``last one``, the one you accessed last. Whatever posts you respond to, Agora will show the last opened message as being the one you are replying to.

Wolfy