hmm.. This isn't happening for me... I'm not sure why this would happen.   Do you have another plugin that is replacing the login form?

I have some similar issue. I had friend moderator module but after installing siteaccess it does not work. when I disable siteaccess it starts to work again. Similar post by someone here http://community.elgg.org/mod/groups/topicposts.php?topic=107842&group_guid=15815

Any clue what is missing?

-----update--------

it seems like the issue is with moderator plugin  and has nothing to do with siteaccess.

I am considering installing your plugin but I'm not sure it is exactly what I need. I want to utilize a captcha feature, but I get the impression yours only activates after 3 unsuccessful login attempts. I'm actually looking for this feature during the registration process. Does it also allow for this?