In case #1 works, in case #2 it do not works. Check the code bellow:
<div class="container">
<div class="row">
<h1>Radio Group #1</h1>
<label class="radio-inline">
<input name="radioGroup" id="radio1" value="option1" type="radio"> 1
</label>
<label class="radio-inline">
<input name="radioGroup" id="radio2" value="option2" checked="checked" type="radio"> 2
</label>
<label class="radio-inline">
<input name="radioGroup" id="radio3" value="option3" type="radio"> 3
</label>
</div>
<div class="row">
<h1>Radio Group #2</h1>
<label for="year" class="control-label input-group">Year</label>
<div class="btn-group" data-toggle="buttons">
<label class="btn btn-default">
<input name="year" value="2011" type="radio">2011
</label>
<label class="btn btn-default">
<input name="year" value="2012" type="radio">2012
</label>
<label class="btn btn-default">
<input name="year" value="2013" checked="checked" type="radio">2013
</label>
</div>
</div>
</div>
You can see it in action here: http://bootply.com/84165