function check_popup_form(FormName) {
    var error = 0;
    var errorMessage = "Errors have occured during the submission of this form!\nPlease make the following corrections:\n\n";
    //var soldoutMessage = "Sorry, this product size has been temporarily sold out.";
    var soldoutMessage = "This class is now full, to be added to the waiting list please email info@dirtyapron.com . \n\nPlease include the name and date of the class you are interested in along with your name and contact details and the number of space you require. We will contact you if places become available.";

    if (FormName.validityTest.value == "Select Product" || FormName.products_id.value == 0) {
        errorMessage = errorMessage + "* You must select a product from the list.\n";
		error = 1;
    }

    if (isNaN(parseInt(FormName.cart_quantity.value)) || FormName.cart_quantity.value <= 0) {
		errorMessage = errorMessage + "* Your quantity must be greater than 0.";
		error = 1;
	}

    // TODO: error checking on sold out.

    if (error == 1) {
        alert(errorMessage);
        return false;
    }

    if (soldOutProducts[FormName.products_id.value] == true) {
        alert(soldoutMessage);
        return false;
    }

    return true;
}