Magento : Use custom error message in shipping method

Question

i have created a shipping method extension in which shipping rate is correctly and even error message is also set when it conditions are sattisfied.

My question is when i am trying to set a the error message it is pulling the default message "Sorry, no quotes are available for this order at this time."

Below is my code

$result = Mage::getModel('shipping/rate_result');
$show = true;
if($show && $price > 0 && !$this->_error){
    $method = Mage::getModel('shipping/rate_result_method');
    $method->setCarrier($this->_code);
    $method->setMethod($this->_code);
    $method->setCarrierTitle($this->getConfigData('title'));
    $method->setMethodTitle($methodName);
    $method->setPrice($price);
    $method->setCost($price);
    $result->append($method);
}else{
    $error = Mage::getModel('shipping/rate_result_error');
    $error->setCarrier($this->_code);
    $error->setCarrierTitle($this->getConfigData('name'));

    if($this->_error){
        $msg = "Shipping rate cannot be calculated.";
    }else{
        $msg = $this->getConfigData('specificerrmsg');
    }
    $error->setErrorMessage($msg);
    $result->append($error);
}
return $result;

Answer 1

For the googlers landing on this page, here is the solution :

To always display the carrier, Magento is looking for the showmethod attribute in your carrier configuration. You should add this code in your config.xml :

<?xml version="1.0" encoding="UTF-8"?>
<config>
    <default>
        <carriers>
            <my_carrier>
                <showmethod>1</showmethod>
            </my_carrier>
        </carriers>
    </default>
</config>

With that, your error message should display.

Answer 2

Code for Error Message:

$message = $this->__('Got an error');
Mage::getSingleton('core/session')->addError($message);

For this case may be you can check your config.xml:

<type>I</type>
<specificerrmsg>This shipping method is currently unavailable. If you would like to ship using this shipping method, please contact us.</specificerrmsg>
<handling_type>F</handling_type>