My JavaScript form isn't validating properly

Hi Experts,
I'm in the middle of an assignment and part of it involves validating a form. I used the code below to validate the form and have checked that the form elements match up with what I have in the JavaScript.
I tested it it with just the first two fields including the email and it worked as expected. When I added the remaining fields only the email address field validates.
Can anyone tell me why?

function validateDetails(myForm){
	var errors = [];
	var customerName = myForm['customerName'].value;
	var emailAddress = myForm['emailAddress'].value;
	var addressLine1 = myForm['addressLine1'].value;
	var addressLine2 = myForm['addressLine2'].value;
	var cTownCity = myForm['townCity'].value;
	var cPostCode = myForm['postalCode'].value;
	var cCardNumber = myForm['paymentDetails'].value;
	
	if(customerName.value == "")
		{errors.push("Please provide your name");}
	
	if(!validateEmail(emailAddress))
	 {errors.push("Please provide a valid email");}
	 
	if (addressLine1.value == "")
	{errors.push("Please provide the first line of your address");}
	
	if(cTownCity.value=="")
	errors.push("Please fill in the Town or City field");
	
	
	if (errors.length>0){
		var errorsDiv = document.getElementById("yourorder");
		
		errorsDiv.innerHTML = errors.join("<br/>");
		return false;
	}
}
function validateQuantity()
{
	var val = this.value;
	if(isNumber())
	{
		document.getElementById("ordererrors").innerHTML = "error";
	}
}
/*validate email addresses*/
function validateEmail(emailAddress){
var emailFormat = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
if(emailAddress.match(emailFormat))
return true;
}

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