steeds error

function checkNumeric(text) {
	if (text.search(/[^0-9]/) == -1) {
		return false;
	} else {
		return true;
	}
}

function checkNumeric(text) {
	if (text.search(/[^0-9]/) == -1) {
		return false;
	} else {
		return true;
	}
}

<form method="post" action="" name="cartForm{id}" id="cartForm{id}" onsubmit="return checkShopForm('{id}');">
<input name="id" id="id" type="hidden" value="{id}" />
<input type="text" name="number" id="number" value="1" size="2" />
<input type="submit" id="submit_addCart" name="submit_addCart" value="Bestel" />
</form>

<form method="post" action="" name="cartForm{id}" id="cartForm{id}" onsubmit="return checkShopForm('{id}');">
<input name="id" id="id" type="hidden" value="{id}" />
<input type="text" name="number" id="number" value="1" size="2" />
<input type="submit" id="submit_addCart" name="submit_addCart" value="Bestel" />
</form>

function checkShopForm(id) {
	var error = 0;
	var error_text = "";
	
	var number = document.forms["cartForm"+id].elements["number"];
	
	if (trim(checkNumeric(number.value)) == true)
	{
		number.className = '';
	} else {
		number.className = 'error';
		error = 1;
		error_text += "Invoer is geen getal\n";
	}
	
	if (error != 0) {
		alert(error_text);
		return false;
	}
}

function checkShopForm(id) {
	var error = 0;
	var error_text = "";
 
	var number = document.forms["cartForm"+id].elements["number"];
 
	if (trim(checkNumeric(number.value)) == true)
	{
		number.className = '';
	} else {
		number.className = 'error';
		error = 1;
		error_text += "Invoer is geen getal\n";
	}
 
	if (error != 0) {
		alert(error_text);
		return false;
	}
}