scilab fails in show_graph()

[syn hedionn]

Hi,
On scilab 5.1.1 linux Ubuntu 9.10
I do :
algo52arcs=[1 2 1 3 1 4 2 3 2 6 3 5 4 5 4 7 5 6 5 7 6 7] -->OK
algo52arcDeb=zeros(length(algo52arcs)/2);algo52arcDeb=zeros(length
(algo52arcs)/2);for k=1:length(algo52arcs), if modulo(k, 2)==1 then
algo52arcDeb((int32(k) / (int32(2))+1))= algo52arcs(k) ,else,
algo52arcFin(int32(k)/int32(2))= algo52arcs(k),
end ,end -->OK

algo52val=[3 3 2 2 5 1 0 2 3 4 2] --
>OK
algo52max=[6 4 3 2 5 5 2 2 3 4 6 ] -->OK

g52=make_graph('grapheMoi',
1,0,algo52arcDeb,algo52arcFin) -->OK

algo52pnts_x=[];;for k=1:11 , algo52pnts_x(k)=cos((k/11)*
(2*3.14)),end -->OK
algo52pnts_y=[];;for k=1:11 , algo52pnts_y(k)=sin((k/11)*
(2*3.14)),end -->OK

g52('node_x')=algo52pnts_x;g52('node_y')=algo52pnts_y
-->OK

But:
show_graph(g52)

!--error 9
Soustraction incohérente.

at line 5 of function ge_dig_bound called by :
line 9 of function ge_set_winsize called by :
line 61 of function edit_graph called by :
line 38 of function show_graph called by :
show_graph(g52)

How can I do to have my graph?