Alternative For InsertRow And InsertCell, Which Is Not Working In Firefox

I have a problem with FireFox. I have written a function to Add rows without submiting the form. This function works fine in IE, but not in FireFox.
The function is :

function createRows(deviceId,deviceType,modelName,ipAddress,macAddress,imageURL)
{
oTable=document.getElementById("tab:tabForm: oTable");

var oRow1=oTable.insertRow(oTable.rows.length);
var aRows=oTable.rows;
var aCells=oRow1.cells;
var oCell1_1=aRows(oRow1.rowIndex).insertCell(aCells.length);
var oCell1_2=aRows(oRow1.rowIndex).insertCell(aCells.length);
var oCell1_3=aRows(oRow1.rowIndex).insertCell(aCells.length);
var oCell1_4=aRows(oRow1.rowIndex).insertCell(aCells.length);
var oCell1_5=aRows(oRow1.rowIndex).insertCell(aCells.length);
var oCell1_6=aRows(oRow1.rowIndex).insertCell(aCells.length);

oCell1_1.innerHTML="<input>";
oCell1_2.innerHTML="";
oCell1_3.innerHTML="<font>"+modelName+"</font>";
oCell1_4.innerHTML="<font>"+ipAddress+"</font>";
oCell1_5.innerHTML="<font>"+macAddress+"</font>";
oCell1_6.innerHTML="<input>";
}

Can anyone please tell me what's the feature that is not supported in Firefox that makes this function not work in the same.