You must not have HTML enabled correctly. I tried this on my test forum, with no problem.
Just to be on the safe side:
1. Only administrators should have access to HTML.
2. Do not enable it where you do not need it.
You can limit HTML at the FORUM, USERGROUP, USER levels... So double check your permissions there.
I am not sure what you are really doing here. It is a very relative link. I know it might just be an example.
Code:
<a href="#link1"></a>
Sorry, I cannot be of more help. I would need to know what you had already tried.