Table showing two header columns

Table showing two header columns

I'm trying to utilize the reflow mode in JQueryMobile 1.3.0 but it never displays full-table even when there's enough space, and it always duplicates the header column. Any help on this? Here's my current code for this table:

<table data-role="table" data-mode="reflow" style=" text-align:center"id="Meindl-Lovejoy-1985-Table-7"  border="1" cellspacing="0" cellpadding="4">
<thead>
<tr>
<th> Composite score </th>
<th> n= </th>
<th> Mean </th>
<th> S.D. </th>
<th> Inter-decile range </th>
<th> Range </th>
</tr>
</thead>

<tbody>
<tr><th> 0 (Open) </th> <td> 24 </td><td> --- </td><td> --- </td><td> -35 </td><td> -49 </td></tr>
<tr><th> 1, 2 </th> <td> 12 </td><td> 30.5 </td><td> 9.6 </td><td> 19-44 </td><td> 18-45 </td></tr>
<tr><th> 3, 4, 5, 6 </th> <td> 30 </td><td> 34.7 </td><td> 7.8 </td><td> 23-45 </td><td> 22-48 </td></tr>
<tr><th> 7, 8, 9, 10, 11 </th> <td> 50 </td><td> 39.4 </td><td> 9.1 </td><td> 28-44 </td><td> 24-60 </td></tr>
<tr><th> 12, 13, 14, 15 </th> <td> 50 </td><td> 45.2 </td><td> 12.6 </td><td> 31-65 </td><td> 24-75 </td></tr>
<tr><th> 16, 17, 18 </th> <td> 31 </td><td> 48.8 </td><td> 10.5 </td><td> 35-60 </td><td> 30-71 </td></tr>
<tr><th> 19, 20 </th> <td> 26 </td><td> 51.5 </td><td> 12.6 </td><td> 34-63 </td><td> 23-76 </td></tr>
<tr><th> 21 (Closed) </th> <td> 13 </td><td> --- </td><td> --- </td><td> 43- </td><td> 40- </td></tr>
</tbody>
</table>