JavaScript calculate function won't work on firefox

[Gianluka]

This function is called onblur when I insert numbers as you can see on this page:

http://www.madebymeworkshops.nl/reserveren-form/reserveren.php

I pass by data with PHP from a reservation page that comes before:

http://www.madebymeworkshops.nl/workshops/particulier/workshop_particulier_beeldhouwen.html

You can just click 'Reserveer Dagworkshop' on the first block 'Short' on light blue.

and this is the javascript:

<script language="JavaScript" type="text/javascript">

function Calculate()

{
   // calculate each line total
   
   var decim = 100;
   var fee = 0;
   
   if(phpformmailer.kortingskaart_fee.checked)
	{
		fee = 4;
		phpformmailer.discount_type.value = "Made by Me! Kortingskaart";
	}
	else
	{
		fee = 0;
		phpformmailer.discount_type.value = "NO-Korting Selected";
	}
	if (phpformmailer.total_bon.value==null || phpformmailer.total_bon.value=="")
	phpformmailer.total_bon.value = 0;
    
	if (phpformmailer.howmany.value == 1)
	phpformmailer.total_costs.value = Math.round(parseFloat(phpformmailer.howmany.value) * parseFloat(phpformmailer.cost.value) * decim) / decim;
	else
	phpformmailer.total_costs.value = Math.round(parseFloat(phpformmailer.howmany.value) * parseFloat(phpformmailer.cost.value) * decim) / decim;

	if (phpformmailer.howmanydiscount.value == 1)
	phpformmailer.totaldiscount.value = Math.round(parseFloat(phpformmailer.howmanydiscount.value) * parseFloat(phpformmailer.originalcost.value) / 100 * 50 * decim) / decim;
	else 
	phpformmailer.totaldiscount.value = Math.round(parseFloat(phpformmailer.howmanydiscount.value) * parseFloat(phpformmailer.originalcost.value) / 100 * 50 * decim) / decim;
   
	if (phpformmailer.howmanygratis.value == 1)
	phpformmailer.totalgratis.value = Math.round(parseFloat(phpformmailer.howmanygratis.value) * 69 * decim) / decim;
	else 
	phpformmailer.totalgratis.value = Math.round(parseFloat(phpformmailer.howmanygratis.value) * 69 * decim) / decim;
	
	phpformmailer.total_off.value = Math.round((parseFloat(phpformmailer.totaldiscount.value) + parseFloat(phpformmailer.totalgratis.value) + parseFloat(phpformmailer.total_bon.value)) * decim) / decim;
	
	phpformmailer.total.value = Math.round(((parseFloat(phpformmailer.total_costs.value)  - parseFloat(phpformmailer.total_off.value)) + fee) * decim) / decim;
	
	
}

</SCRIPT>

[Dormilich]

Firefox does not automatically wrap names/IDs into JavaScript variables. the HTML way of accessing form elements is: document.form_n ame.element_nam e.