Image hover effects not working

. The CSS has been added
`.post-image {
position: relative;
overflow: hidden;
}
.post-image img {
max-width: 100%;

-moz-transition: all 0.3s;
-webkit-transition: all 0.3s;
transition: all 0.3s;
}
.post-image:hover img {
-moz-transform: scale(1.2);
-webkit-transform: scale(1.2);
transform: scale(1.2);
}

even after adding this code in simple css or additional css this code is not working at all. can you please help me in fixing this issue?

Thanks..