gnuplot> nset obj 2 : invalid command

[lo]

hello,

I have installed octave 3.3.51 on a Linux Suse 11.2;

running the following (not representative of what I am doing or even 
meaningful, I am simply trying to reduce my problem...)


h = figure;
t = 0:0.1:6.3;
for n = 1 : 9
        hc = plot(t,cos(t), "o", "markersize", 3, "markerfacecolor", "g");
        pause(1);
        delete(hc);
end


I get 9 times

gnuplot> nset obj 2
         ^
         line 0: invalid command

in the octave window;

how can I avoid this ?
thanks for the help !

regards,
Laurent