Check whether you have added
<thead></thead>
<tbody></tbody>
I’ve resolved this problem by adding those.
So basically the structure must be like:
<table>
<thead>
<tr>
<th></th>
<th></th>
</tr>
</thead>
<tbody>
<tr>
<td></td>
<td></td>
</tr>
</tbody>
</table>