code acting crazy

[nana]

hello i am having a very strange problem here.

$tot_trade=tep_db_query("select sum(vac_three) as tot_trade from orders where date_format(date_purchased,'%m/%d/%Y') >= '{$_POST['start_date']}' and date_format(date_purchased,'%m/%d/%Y') <= '{$_POST['end_date']}'");
 $row_trade=tep_db_fetch_array($tot_trade);
$tot_mon=tep_db_query("select sum(account_number) as tot_mon from orders where date_format(date_purchased,'%m/%d/%Y') >= '{$_POST['start_date']}' and date_format(date_purchased,'%m/%d/%Y') <= '{$_POST['end_date']}'");
 $row_mon=tep_db_fetch_array($tot_mon);

and futhur down i have

<tr>
                 <td width="34%" align="right" class="dataTableContent"><b>Total labor</b></td>
                 <td width="1%"> </td>
                 <td width="65%" class="dataTableContent"><?php echo $row_mon['tot_mon'];?></td>
               </tr>
                <tr>
                 <td width="34%" align="right" class="dataTableContent"><b>Total trade in value</b></td>
                 <td width="1%"> </td>
                 <td width="65%" class="dataTableContent"><?php echo $row_trade['tot_trade'];?></td>
               </tr>

i get the correct or at least close to correct value when i am searching in some of the fields but not the others here vac_three gives me a value that is close but account_number gives me a number but it is not even close

i need to get the total sum of those fields within the dates both are decimal in the db