That option is only relevant to the published parameter value, not to the reader itself.

Have you tried setting "Ignore failed readers" to Yes in the workspace parameters?

Thanks @david_r, that helped. Didn't know about that parameter.

But now - when starting the workspace in batch - no features are written. When starting the workbench everything works fine. Is that problem linked to that parameter?! Or is there anything different wrong...?!

What does the log file say?

I looked closer to the log and the batch file. It turned out it was a typing error. -.-