in general do applications with only some EXECUTE statements work (I have a lot of them for copy & synchronization files and data and various exporting & printing tasks - and quite important I'm always logged in on the server and some tasks run not directly else the qvw-execution runs a windows tasks which then runs the real batch).
If there are problems they are most often related to missing access-right, security-topics and user-configurations. In your case could be the last mentioned user-configurations the reason. Then if it worked by manually triggering the task within the qmc and not by a scheduled task which very probably runs without any user is logged in into the server. This meant the qvw with the EXECUTION runs with the access rights from the server-user but the started cmd-statement or batch runs without a looged in user only with a system default-user which probaly had not the proper access-rights and other configurations.
that's what I thought - the server blocks the execution of that command-line COPY command. But why is there no document_log telling me so?
Well, never mind. I changed the script now so that the qvd_files - created every hour - are just loaded and the data is then stored away again.