Hello Marco,
Thank you for your message.
Am I right in assuming that you use Viewer of version 7.0.0.1 and Host of an older version (perhaps, 6.10.10.0 or an older version), i.e. mismatching versions of Remote Utilities? If this is the case, then the issue occurs because starting version 7 the File Transfer protocol has been re-written from the ground up in order to improve the overall speed and performance of the File Transfer mode. This means that the File Transfer mode will only work if Viewer and Host are
both version 7.x.x.x. For more information on the updated File Transfer mode please see
this blog post.
Please try updating your Host to the latest 7.0.0.1 version as well by following
this guide on updating Remote Utilities.
Hope that helps.