list-item imbricaton in ui-tabs bug ?

list-item imbricaton in ui-tabs bug ?


hello,
I have a simple form in a jquery-ui tab (from theme-roller demo):
<div id="tabs">
<ul>
<li class="ui-tabs-nav-item"><a
href="#fragment-1">Form 1</a></li>
<li class="ui-tabs-nav-item"><a
href="#fragment-2">Form2</a></li>
</ul>
<div id="fragment-1">
<form action="#" id="testForm" class="required">
<ol class="forms">
    <li><label>Sign Up for the Following <span class="required">*</span></
label>
        <ul>
        <li><input type="checkbox" name="info1" id="info1" /><label
for="info1">Information 1</label></li>
        <li><input type="checkbox" name="info2" id="info2" /><label
for="info2">Information 2</label></li>
        <li><input type="checkbox" name="info3" id="info3" /><label
for="info3">Information 3</label></li>
</ul>
    </li>
</ol>
</form>
</div>
<div id="fragment-2">
...
and firebug gives the error :
elem is undefined
[Break on this error] var id = elem[ expando ];
when I suppress the ul-li that contains checboxes
I have no error:
    <li><label>Sign Up for the Following <span class="required">*</span></
label>
<input type="checkbox" name="info1" id="info1" /><label
for="info1">Information 1</label>
<input type="checkbox" name="info2" id="info2" /><label
for="info2">Information 2</label>
<input type="checkbox" name="info3" id="info3" /><label
for="info3">Information 3</label>
    </li>
It seems that list item imbrication in a tab leads to this error.
Is that something already known ?
Thanks
NB: of course no error appears when it is outside of the jquery-ui-
tab ....