validation part is not working

I have created one classic ASP page.It Contains two table inside the common table. I have some controls on both two tables. Validation part is not working while submit the page. If i removed one table part of coding validation part is working fine.

Can somebody help me? I was struggling from past two weeks.

My coding structure is as follow as 

<table>

<tr>

<td>

<table>

some controls--------

</table>

</td>

<table></table>

<td>

</td>

</tr>

</table>