Magento 1.9 : Class 'Mage_Creditmemoexport_Helper_Data' not found

Question

I am creating a module for exporting Creditmemo data in xml but I am getting following error. I have checked everything but I am unable to find the bug please help me.

Config.xml

<?xml version="1.0" encoding="UTF-8"?>
<config>
    <modules>
        <Ninobambino_CreditmemoExport>
            <version>1.0.0</version>
        </Ninobambino_CreditmemoExport>
    </modules>
    <global>
        <helpers>
            <Ninobambino_CreditmemoExport>
                <class>Ninobambino_CreditmemoExport_Helper</class>
            </Ninobambino_CreditmemoExport>
        </helpers>
        <models>
            <Ninobambino_CreditmemoExport>
                <class>Ninobambino_CreditmemoExport_Model</class>
            </Ninobambino_CreditmemoExport>
        </models>
        <resources>
            <Ninobambino_CreditmemoExport_setup>
                <setup>
                    <module>Ninobambino_CreditmemoExport</module>
                </setup>
            </Ninobambino_CreditmemoExport_setup>
        </resources>
        <events>
            <sales_order_creditmemo_save_after>
                <observers>
                    <Ninobambino_CreditmemoExport_order_creditmemo_save_after>
                        <type>singleton</type>
                        <class>Ninobambino_CreditmemoExport_Model_Observer</class>
                        <method>creditmemoExport</method>
                    </Ninobambino_CreditmemoExport_order_creditmemo_save_after>
                </observers>
            </sales_order_creditmemo_save_after>
        </events>
    </global>
</config>

Data.php

<?php
class Ninobambino_CreditmemoExport_Helper_Data extends Mage_Core_Helper_Abstract
{
    const LOG_ENABLED_CONFIG_PATH = 'productimport/general_config/log_enabled';
    const LOG_FILE_NAME = 'creditmemoexport.log';
    /**
     * Utility function to log a message to the log file, if logging is enabled
     * @param string log message
     */
    public function log($message) {
        if (Mage::getStoreConfig(self::LOG_ENABLED_CONFIG_PATH)) {
            Mage::log($message, null, self::LOG_FILE_NAME);
        }
    }
}

Answer 1

You have to change below code

<helpers>
    <Ninobambino_CreditmemoExport>
         <class>Ninobambino_CreditmemoExport_Helper</class>
    </Ninobambino_CreditmemoExport>
</helpers>

Here change Ninobambino_CreditmemoExport to creditmemoexport

Then to use your helper function use below code

Mage::helper('creditmemoexport')->yourMethod()

Note: Alias name for helper, models and resources node should be in lowercase, you can also use your module name(without namespace) in lowercase for this

Update: your nodes for helper, models and resource should be like below code

<helpers>
    <creditmemoexport>
        <class>Ninobambino_CreditmemoExport_Helper</class>
    </creditmemoexport>
</helpers>
<models>
    <creditmemoexport>
        <class>Ninobambino_CreditmemoExport_Model</class>
    </creditmemoexport>
</models>
<resources>
    <creditmemoexport_setup>
        <setup>
            <module>Ninobambino_CreditmemoExport</module>
        </setup>
    </creditmemoexport_setup>
</resources>