I get "The system cannot find the batch label specified" error even though label exists.
The problems doesn't reproduce when I copy "Execute Windows batch command" text into .bat file and run it.
I've discovered that line endings are NOT CRLF in the batch script stored in config.xml - but they should be.

See http://stackoverflow.com/questions/232651/why-the-system-cannot-find-the-batch-label-specified-is-thrown-even-if-label-ex for explanation.