Yasnippet, Sweave: How to make snippets work from .Rnw files?

Question

I use yasnippet's defined in ~/.emacs.d/plugins/yasnippet-0.6.1c/snippets/text-mode/latex-mode to insert small pieces of code when working with LaTeX. I recently started to use Sweave and therefore work on .Rnw files. However, I noticed that the (ya)snippets don't work anymore - hitting TAB after a trigger word just does not expand the defined snippet. Instead, nothing happens. I thought that's a simple problem to solve, just copy the snippets to ~/.emacs.d/plugins/yasnippet-0.6.1c/snippets/text-mode/rnw-mode or .../noweb-mode. But that did not work either (meaning that hitting TAB does not expand trigger words). What I can do, however, is M-x yas/expand right after the trigger word, so it's working, but just not with TAB.

How can I use yasnippets from .Rnw files?

Update 1

I found http://groups.google.com/group/smart-snippet/browse_thread/thread/8206a23037f598b1/39ed819692df63ad?lnk=gst&q=rnw#39ed819692df63ad I have exactly that problem -- <tab> is bound by noweb-mode. However, the solution posted in the last post does not work for me/does not seem to have an effect on the problem (so, as above, TAB-expansion of trigger words does not work).

As described in that post, the mode changes from LaTeX to noweb depending on where the point is in the .Rnw file. I only need my LaTeX macros to expand when in LaTeX mode (of course).

In case this matters, I work with Emacs 24 on Mac OS X 10.7.3.

Update 2

C-h k TAB leads to (either with or without the solution posted on the above line):

<tab> runs the command noweb-indent-line, which is an interactive Lisp function
in `noweb-mode.el'.

It is bound to <tab>.

(noweb-indent-line)

Indent the current line according to mode, after narrowing to this chunk.

So obviously, TAB is used by noweb.

Update 3

When the point is in a LaTeX part of the .Rnw file, then the modes displayed in the mode line are: LaTeX/MP Ref Fly yas pair vl Wrap Fill Noweb NWFL. If the point is in an R chunk of the file, then the modes are: ESS[S] [none] Rox Fly ElDoc pair vl Wrap Noweb NWFL. So indeed, the modes change when out of/within R chunks. However, I still can't TAB-expand snippets. My .emacs contains (which is obviously not working as expected):

(add-hook 'LaTeX-mode-hook
  '(lambda ()
     (make-variable-buffer-local 'yas/trigger-key)
     (setq yas/trigger-key [tab])))

Answer 1

Finally, the problem is solved. One needs to switch to the tighter-tab branch of yasnippet. See https://github.com/capitaomorte/yasnippet/issues/231 for more details