WooCommerce Upload My File plugin won't activate

Hi there,

I’m using the theme Responsive and want to start using the WooCommerce Upload My File plugin. After installing, once I click ‘activate’ in the plugin menu, I get a red text box saying:

‘WooCommerce is not active. Please activate plugin before using WooCommerce Upload My File plugin.’

Have re-installed the plugin but that won’t help. Does anyone know how to solve this?

Thanks in advance!