Traversing Table with merged cells

[azareth]

URGENT: guys i really need your help with this. I have been debugging my program for days but it doesn't seem to be improving
this is the code for the table layout:

<table border="1" id="COT_Table" onclick="getTableID(this)">
<td rowspan="3" scope="row">COT</td>
<th colspan="4" scope="col">SFAL</th>
</tr>
    <tr>
    <td colspan="2" scope="col">Temperature</td>
    <td rowspan="2" scope="row">vol kL@air</td>
    <td rowspan="2" scope="row">vol kL@15C</td>
    <tr><td>thermo probe</td><td>vessel thermo</td></tr>
    </tr>
<tr><td>1P</td><?php TableCells_Temp("COT","1","2");?><?php TableCells2("2");?></tr>
<tr><td>1S</td><?php TableCells_Temp("COT","2","2");?><?php TableCells2("2");?></tr>
<tr><td>2P</td><?php TableCells_Temp("COT","3","2");?><?php TableCells2("2");?></tr>
<tr><td>2S</td><?php TableCells_Temp("COT","4","2");?><?php TableCells2("2");?></tr>
<tr><td>3P</td><?php TableCells_Temp("COT","5","2");?><?php TableCells2("2");?></tr>
<tr><td>3S</td><?php TableCells_Temp("COT","6","2");?><?php TableCells2("2");?></tr>
<tr><td>4P</td><?php TableCells_Temp("COT","7","2");?><?php TableCells2("2");?></tr>
<tr><td>4S</td><?php TableCells_Temp("COT","8","2");?><?php TableCells2("2");?></tr>
<tr><td>5P</td><?php TableCells_Temp("COT","9","2");?><?php TableCells2("2");?></tr>
<tr><td>5S</td><?php TableCells_Temp("COT","10","2");?><?php TableCells2("2");?></tr>
<tr><td>P/L</td><?php TableCells_Temp("COT","11","2");?><?php TableCells2("2");?></tr>
<tr><td>OBQ</td><?php TableCells_Temp("COT","12","2");?><?php TableCells2("2");?></tr>

<tr>
<td></td>
<td><label>temp taken by</label><input type="decimal" name="r_132" value="" maxlength="10" size="5"/></td>
<td><label>temp taken by</label><input type="decimal" name="r_133" value="" maxlength="10" size="5"/></td>
<td>0</td>
<td>0</td>
</tr>
</table>

the functions i've used:

<?php function TableCells2($nColumn){
for($i=0;$i<$nColumn;$i++){?>
        <td><input type="text" value="1" onchange="Formula_COT(this)" size="10%"></td>
<?php }}?>

i used TableCells2 to create the input boxes for the computation where i need to get the sum their sum vertically and subtract the OBQ from their total.

<?php function TableCells_Temp($TableName,$rowNum,$nColumn){
for($i=0;$i<$nColumn;$i++){?>
    <td><input type="decimal" name="<?php echo $TableName.$rowNum."_1"; ?>" value="" maxlength="10" size="10"/></td>

<?php }}?>

this 2nd function is for inputs only, it doesn't need any computation

and finally this if for traversing the table and computation

var TableID = getTableID(tableID);
function getTableID(tableID){
    while (tableID.nodeName.toLowerCase() != 'table')
        tableID = tableID.parentNode;
    TableID = tableID.id;
}

function getColumnCount() { 
return document.getElementById(TableID).getElementsByTagName('tr')[0].getElementsByTagName('td').length; 
} 

function getRowCount() { 
return document.getElementById(TableID).rows.length; 
} 

function Formula_COT(ths) {
        var lastCol = getColumnCount()-1; 
        var lastRow = getRowCount()-1; 
        var table = document.getElementById(TableID); 
        var rowSum; /*Summation of all the values in of rows*/
        var columnValue; 
        if(ths == 'on'){

            for(var b=0;b<lastRow;b++){
                rowSum = 0;
                for(var i=0;i<lastCol-1;i++){ 
                    columnValue =  table.rows[i].cells[b].childNodes[0].value;
                    if(columnValue != '' && !isNaN(columnValue)){
                        rowSum = eval(rowSum) + parseInt(columnValue);
                    }
                    table.rows[lastRow].cells[b].innerHTML = rowSum; 
                }
            }

        }else{
            var cIndex = ths.parentNode.cellIndex; 
            rowSum = 0; 
            for(var i=0;i<lastRow;i++) {
                columnValue =  table.rows[i].cells[cIndex].childNodes[0].value;
                if(columnValue != '' && !isNaN(columnValue)){
                    rowSum = eval(rowSum) + parseInt(columnValue);
                }
            } 
            table.rows[lastRow].cells[cIndex].innerHTML = rowSum; 
        }
    } 

the program doesn't compute anything ..
i know this seems to be boring bec of the long code but i urgently need help in this.
your help is very much appreciated . thanks in advance