problem export csv,copy and excel

I want exports csv,copy, excel but datables unknown propetys colspan or rowspan of table.
Example :
<thead>
<tr>
<th align="center" colspan="8" class="table-title" ><center><font color="#ffff00"><strong>Bảng</strong></font>
</center></th>
</tr>
<tr>
<th width="40" align="left" class="table-title"><center><font color="#ffff00"><strong>Sửa</strong></font>
</center></th>
<th width="40" align="left" class="table-title"><center><font color="#ffff00"><strong>Xóa</strong></font>
</center></th>
<th width="40" class="table-title"><center>
<font color="#ffff00"><strong>STT</strong>
</font>
</center>
</th>
<th align="left" class="table-title" width="303">
<center>
<font color="#ffff00"><strong>Tên đơn vị</strong></font>
</center>
</th>
<th align="left" class="table-title" width="129">
<center>
<font color="#ffff00"><strong>Số điện thoại trưởng đơn vị</strong></font>
</center>
</th>
<th align="left" class="table-title" width="129">
<center>
<font color="#ffff00"><strong>Số điện thoại bàn phó đơn vị</strong></font>
</center>
</th>
<th align="left" class="table-title" width="129">
<center>
<font color="#ffff00"><strong>Số điện thoại đơn vị</strong></font>
</center>
</th>
<th align="left" class="table-title" width="129">
<center>
<font color="#ffff00"><strong>Email phòng ban</strong></font>
</center>
</th>
</tr>
</thead>
It unknows colspan="8" when export