My custom extension is not visible on admin panel Magento 2.0 - magento2

Question

I installed my custom extension via composer.
I can confirm that app/code/vendor/package_name generated on the server by composer.
However,on admin panel under stores/configuration/advanced I can not see my extension.
What I've tried so far are as following ;
Flushing Magento 2.0 cache and disabling caching
Changing extension file permissions to 777
Deleting files under var/cache manually
Logging out and logging in again
None of them solved my problem.
How can I see my custom extension under admin stores / configuration / advanced on Magento 2.0 ?
I am not sure if it any helps but I posted my config.xml and module.xml
Thanks in advance,
<?xml version="1.0" ?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../../lib/internal/Magento/Framework/Module/etc/module.xsd">
<module name="Fusion_CODFee" schema_version="0.0.1"></module>
</config>
<?xml version="1.0" ?>
<config>
<modules>
<Fusion_CODFee>
<version>0.1.0</version>
</Fusion_CODFee>
</modules>
</config>

Answer 1

According to me setup_version is missing from module.xml. It should be like this :
<?xml version="1.0" ?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../../lib/internal/Magento/Framework/Module/etc/module.xsd">
<module name="Fusion_CODFee" schema_version="0.0.1" setup_version="0.0.1"></module>
</config>

Answer 2

you shoul try php bin/magento setup:upgrade command so that your magento upgrade itself with the new extension, also check for config.php in app/etc folder ,your module should be there if is active in case it is not then under array() tag add this "Fusion_CODFee=>1" and then run upgrade command in your rootdirectory, it might help you.

Answer 3

I've tried following code that's working for me please have look
Fusion\CODFee\etc\module.xml
<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
<module name="Fusion_CODFee" setup_version="2.0.0">
</module>
</config>
Now next you have to register your module with registration.php
create registration.php under Fusion\CODFee\registration.php and put below code inside it.
<?php
\Magento\Framework\Component\ComponentRegistrar::register(
\Magento\Framework\Component\ComponentRegistrar::MODULE,
'Fusion_CODFee',
__DIR__
);
Now clearing you cache and if still not working then fire below command from your root directory of magento installation
If your system is ubuntu then => sudo php bin\magento setup:upgrade or for window system remove sudo
then change permission and that's it
Let me know if still have any query