Config type for columns

[VIE-Flamingo]

I did exactly as your Readme-Currency List Column part but I got this problem "Target class [myauthor.myplugin.helper] does not exist.".
It worked perfectly for form field config, do you have any ideas about my problem?

[daftspunk]

Code for this is here: https://github.com/responsiv/currency-plugin/blob/master/Plugin.php#L105