Background image wont show on the whole page

Hi i have a problem with my wordpress site - i used this css to change the background of page :

.page-id-689 #primary { background: url('http://ift.tt/1Z4CIYd') no-repeat center center !important;

-webkit-background-size: cover !important;

-moz-background-size: cover !important;

-o-background-size: cover !important;

background-size: cover !important;

min-height:100% !Important;

}

---

the problem is that the background wont show on the whole page ( Screenshot : http://ift.tt/1j0MDx4 ).

I already tried :

.page-id-287 #page_wrapper { height:100% !important; margin: 0px auto; }

---

html, body { height: 100% }

---

i also tried setting min-height to 100 % - wont work

!!! the problem is solved when i set the height to 1200px in #primary but it also causes huge problems in lower resolutions. Can someone help me with this ?

via Chebli Mohamed