Nested div elements: 2.5 Beta

I am unable to create nested divs or similar mark-up using the 2.5 Beta editor.
e.g

<div class="boxout">
<p>Some content</p>
</div>

or

<div style="float:right">
<div style="border:solid 1px #CCCCCC; padding:5px">
<p>Some content</p>
</div>
</div>

If I try to add a paragraph or div inside an already existing div, it simply replaces the outer element.

I could do this in previous FCKeditor versions.
Am I doing something wrong? Is there a configuration option I should set?

Cheers