It means that you need to add to your TeX installation. What is the exact name of the template that you are using?
--- On Wed, 8/4/10, Guldariya Nurbaeva <g.nurba...@gmail.com> wrote: > From: Guldariya Nurbaeva <g.nurba...@gmail.com> > Subject: A&A template file problem > To: lyx-users@lists.lyx.org > Received: Wednesday, August 4, 2010, 6:49 AM > Dear LyX developers, > > > I need to write a paper in Astronomy&Astrophysics > journal, but when I try to open the template file aa.lyx, I > get the message > > "The layout file requested by this document, > aa.layout, > is not usable. This is probably because a LaTeX > class or style file required by it is not > available. See the Customization documentation > for more information. > LyX will not be able to produce output." > > Could you tell me how to fix it? Or if you have some > A&A example LyX files - please send me them. > > I use Mac Book Pro, SnowLeopard system, LyX1.6.7 > > Thank you, > > Daria Nurbaeva