contour-line (gras-qgis)

Hi,
i'm tring to visualize in qgis-0.8.2 (osx)
a contour map (generate in grass with r.contour)
when i "ask" the map, qgis give me this result:

http://img125.imageshack.us/img125/5803/immagine19kw6.png

it:  Nessun elemento trovato. Nessuna geometria presente sul  
vettoriale selezionato nel punto del click
en:  can't finde any elements. Nothing geometry on the vector Layer  
in the click point

Strange issue, beacouse grass is able to load its attribute, and  
display it when i ask with "d.what.vect"
and an other strange things is that the vector attribute table is  
load correctly in qgis, see :


http://img49.imageshack.us/img49/8426/immagine18bv1.png

then in qgis layer options i can set a different color to a different  
level...

http://img125.imageshack.us/img125/8614/immagine20re0.png

i've this problem only with contour line.

thanks for any help!
Massimo.