gplot w l linestyle doesn't work

[David Larom]

in gnuplot, i can say:
set linestyle 1 lt 1 lw 1 pt 1 ps 1
plot sin(x) w l ls 1
and it does the graph with lines, linestyle 1, as requested.

But in Octave, the equivalent doesn't work:
gset linestyle 1 lt 1 lw 1 pt 1 ps 1

gshow linestyle works fine; it displays
linestyle 1, linetype 1, linewidth 1, pointtype 1, pointsize 1

and
a=-10:.1:10;
b=[a' sin(a')];

Now,

gplot(b) 

works fine, but

gplot(b) w l linestyle 1

gives the error message 
error: 'linestyle' undefined near line 52 column 14
error: evaluating expression near line 52, column 14
error: evaluating plot style command