octave 9.1 w 64 bit err between func(*) arg and index using()

[DuyKy Nguyen]

dear my Octave heros
I'm retiree after 35 yr as R&D Engwith dusability but still love geek working
Due to my limit finance I still using my old w7 64
I really love Octave per its nice and great feature over MLab even I've used MLab since 1993
Recently I run into problem with my Octave 9.1on my w7 -64b
I could not install 9.2
The error is it report my function fgg
##############################################################################
function [z gg]= fgg (xx )
x=xx(1);
y=xx(2);
    gg=ones(2,1);
    z =   (1 - x)^2 + 100*(-x^2 + y)^2;
Fx =   -400*x*(-x^2 + y) + 2*x - 2;
Fy =   -200*x^2 + 200*y;
gg(1)=Fx;
gg(2)=Fy;
endfunction
##############################################################################
with xx= [ 1 2]
[z gg]= fgg (xx )
it raise err in interpreting () in fgg not as arg but as index
Sincer regards
DuyKy Nguyen, PhD EE, retiree