display: flex not working on Internet Explorer

My flex container:

.back_pattern {
    display: flex;
    display: -ms-flexbox;
    -ms-flex-pack: center;
    flex-direction: column;
    align-content: center;
    justify-content: center;
    min-height: 100vh;
    width: 100%;
}

On other browsers everything works.
ie11 : http://take.ms/68dHo ;
chrome : http://take.ms/JhcEH
What's problem?