#114 Failed opening required './inc/magmi_defs.php'

[Julio Cezar Kronbauer]

I'm trying to use the product import engine data pump:

Magmi_DataPumpFactory::getDataPumpInstance('productimport')

It generates the following error:

Fatal error: require_once() [function.require]: Failed opening required './inc/magmi_defs.php' (include_path='/path/to/magento/dir/app/code/local:/path/to/magento/dir/app/code/community:/path/to/magento/dir/app/code/core:/path/to/magento/dir/lib:.:/usr/lib/php:/usr/local/lib/php:/path/to/magento/dir/magmi/inc:/path/to/magento/dir/magmi/integration/inc:/path/to/magento/dir/magmi/engines') in /path/to/magento/dir/magmi/engines/magmi_productimportengine.php on line 11

I'm using:

Magento 1.9.0.1
PHP 5.2.17

Are there any system requirements to use MAGMI? There are Magento and PHP installs MAGMI works perfectly.