Just checked with with the changed .layout-file in the layout-folder of the installation tree (I am working on a Vista machine). The funny thing is that the code is correctly presented in the LyX-LaTeX preview window and can be well digested by LaTeX after re-export. Is it possible that the problme is just a question of presentation in LyX while there compiling the code with LyX runs into problems.
Thanks for any input. Best wishes, J.