New Post: Problem with ul in Visual Editor

When I try to create an unordered list in the Visual Editor by writing some text, selecting it and chosing "Unordered List" from the style dropdown, instead of surrounding it with an ul-Block I get the following HTML markup:

<div style="margin-left: 2em">Test</div>

This is the relevant part of my Frontend/Config/VisualEditor/common.xml:

<radiogroup>
      <format id="h1" label="Heading H1" image="" notes="Big heading" block="h1">
        <select />
      </format>
      <format id="h2" label="Heading H2" image="" notes="Small heading" block="h2">
        <select />
      </format>
      <format id="h3" label="Heading H3" image="" notes="Very Small heading" block="h3">
        <select />
      </format>
      <format id="p" label="Paragraph" image="" notes="Paragraph" block="p">
        <select />
      </format>
        <format id="ul" label="Unordered List" image="" notes="ul" block="ul">
            <select />
        </format>
    </radiogroup>

What is going on? Could anybody please shed some light on the issue, I am completely clueless.