Wrong Syntax For FormatNumber() ? I'm Stuck.

I have a function for totalling decimal values provided in textboxes
that form a column on a webpage. This script should total the values
in the textboxes, displaying the result in the final
'optotalprogtime' text box formatted as a decimal.

Here is what I've got so far, but I'm getting annoying "object
expected" errors on the line where I attempt to format the number (as
indicated by the comment below)


//realtime calculation formating as minutes (decimals)
function opprogtotalcol() {
alert("in opprogtotalcol");
document.getElementById('optotalprogtime').value = 0;
for (var rowNumber =1; rowNumber <= 12; rowNumber++){
document.getElementById('optotalprogtime').value =
parseFloat(document.getElementById('optotalprogtim e').value) +
parseFloat(document.getElementById('opprogmin' + rowNumber ).value);
}
if(!isNaN(document.getElementById('optotalprogtime ').value)){
//only works for numbers
document.getElementById('optotalprogtime').value =
formatNumber(document.getElementById('optotalprogt ime').value,
2);//format number here
}
}

Any insight would be appreciated.

To head off concerns about wrapping code correctly, my code is
wrapping pretty bad in this form, but in the acutal page I have long
lines that do not wrap.