Ok Jack, thanks for your effort, I appreciate it.
Turns out that the original formula partially uses the wrong series (the
last two), and that during the renaming stage in order to reduce the
line length that error was implicitly corrected without anyone noticing
until now.
So it's not a gretl bug at all!
Sorry for the noise, we really should have cross-checked with a
different software first. But hey, we're all only using gretl ;-)
thanks,
sven