#701 Concatenation issues

[Patrice12345]

If I add a DVD video Using "Add DVD Titles" to get all its elements then make a menu and try to create a new DVD, I would like to do that without encoding and therefore I set the encoding option to "Copy" but 1) I cannot choose the option" Do not Multiplex/transcode" in the Title properties which is greyed out (why?) and 2)the "create DVD command" ends up with an error message telling me that the transcoding (which I would have liked to avoid!) cannot deconcatenate VTS_01_1 VOB and VTS_01-2 VOB! How can I avoid this. My source video seems DVD compliant but, if that is the problem, how can I be sure? Thanks a lot for your help? Note that this does not happen if ma source dvd only contains one element ie. VTS-01_1 VOB