Transition not working

.GridViewHeader {
	background: #4c4c4c; /* Old browsers */
	background: -moz-linear-gradient(top, #4c4c4c 0, #595959 12%, #666666 25%, #474747 39%, #2c2c2c 50%, #000000 51%, #111111 60%, #2b2b2b 76%, #1c1c1c 91%, #131313 100%); /* FF3.6+ */
	background: -webkit-gradient(linear, left top, left bottom, color-stop(0,#4c4c4c), color-stop(12%,#595959), color-stop(25%,#666666), color-stop(39%,#474747), color-stop(50%,#2c2c2c), color-stop(51%,#000000), color-stop(60%,#111111), color-stop(76%,#2b2b2b), color-stop(91%,#1c1c1c), color-stop(100%,#131313)); /* Chrome,Safari4+ */
	background: -webkit-linear-gradient(top, #4c4c4c 0,#595959 12%,#666666 25%,#474747 39%,#2c2c2c 50%,#000000 51%,#111111 60%,#2b2b2b 76%,#1c1c1c 91%,#131313 100%); /* Chrome10+,Safari5.1+ */
	background: -o-linear-gradient(top, #4c4c4c 0,#595959 12%,#666666 25%,#474747 39%,#2c2c2c 50%,#000000 51%,#111111 60%,#2b2b2b 76%,#1c1c1c 91%,#131313 100%); /* Opera 11.10+ */
	background: -ms-linear-gradient(top, #4c4c4c 0,#595959 12%,#666666 25%,#474747 39%,#2c2c2c 50%,#000000 51%,#111111 60%,#2b2b2b 76%,#1c1c1c 91%,#131313 100%); /* IE10+ */
	background: linear-gradient(to bottom, #4c4c4c 0,#595959 12%,#666666 25%,#474747 39%,#2c2c2c 50%,#000000 51%,#111111 60%,#2b2b2b 76%,#1c1c1c 91%,#131313 100%); /* W3C */
	filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#4c4c4c', endColorstr='#131313',GradientType=0 ); /* IE6-9 */
	min-height: 25px;
	cursor: pointer;
	-moz-transition: background 1s ease-in 1s;
	-o-transition: background 1s ease-in 1s;
	-webkit-transition: background 1s ease-in 1s;
	transition: background 1s ease-in 1s;
}
 
GridViewHeader:hover {
	background: -moz-linear-gradient(top,  #f9e772 0, #fcf7cf 49%, #efd01f 100%); /* FF3.6+ */
	background: -webkit-gradient(linear, left top, left bottom, color-stop(0,#f9e772), color-stop(49%,#fcf7cf), color-stop(100%,#efd01f)); /* Chrome,Safari4+ */
	background: -webkit-linear-gradient(top,  #f9e772 0,#fcf7cf 49%,#efd01f 100%); /* Chrome10+,Safari5.1+ */
	background: -o-linear-gradient(top,  #f9e772 0,#fcf7cf 49%,#efd01f 100%); /* Opera 11.10+ */
	background: -ms-linear-gradient(top,  #f9e772 0,#fcf7cf 49%,#efd01f 100%); /* IE10+ */
	background: linear-gradient(to bottom,  #f9e772 0,#fcf7cf 49%,#efd01f 100%); /* W3C */
	filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#f9e772', endColorstr='#efd01f',GradientType=0 ); /* IE6-9 */
	color:black;
}