CSS zoom on icons

I created the following CSS in order to have a progressive zoom effect on the icons:
.image-zoom {
-webkit-transition: all .2s ease-out;
-moz-transition: all .2s ease-out;
-ms-transition: all .2s ease-out;
-o-transition: all .2s ease-out;
transition: all .2s ease;
}
.image-zoom: hover {
-webkit-transform: scale (1.2);
-moz-transform: scale (1.2);
-ms-transform: scale (1.2);
-o-transform: scale (1.2);
transform: scale (1.2);
}
By applying this CSS on the icons, I have a zoom, but immediately, not progressive.
See: https://www.upvierzon.org
Where is the problem ?
Thank you