thks KAT for your prompt answer.
just to let you know that i did what you told me . many times . i even chnged the position of my dish .
it seems that something is wrong with either my dish or the lnbf.
because i took my rcvr to my neighbourg house and connected it to his LNB AND IT WORKED PERFECTLY.
now am thinking of buying a new dish a round one not oval as delivered by
sadoun . hoping it will work.