scss linear gradient not working

1background: -webkit-gradient(linear, left top, right top, color-stop(0%, transparent), color-stop(50%,#fff), color-stop(100%,transparent)); /* Chrome, Safari4+ */
2background: -webkit-linear-gradient(left, transparent 0%,#fff 50%,transparent 100%); /* Chrome10+, Safari5.1+ */
3background: -moz-linear-gradient(left, transparent 0%,#fff 50%,transparent 100%);    /* FF3.6+ */
4background: linear-gradient(to left, transparent 0%,#fff 50%,transparent 100%);      /* W3C */