CSS Image Sprite - Invalid Property Value -

learning use sprite menu right following tutorial. reason, chrome giving me 'invalid property value' on of background-position lines. first one, position 0 0 works fine, other 2 -33 0 , 0 -33 won't work, means site showing 1 button right , hover isn't applied. picture using right 197x65

  #sidebar .content .follow {                             display: block; float: left; height: 32px;                             background-image: url('http://s23.postimg.org/8ltupgj0r/follow.png'); text-indent: -9999px;                               margin-right: 5px;                             }                             #sidebar .content .follow a.fb {                                width: 32px; background-position: 0 0; }                            #sidebar .content .follow a.twit {                                width: 32px; background-position: -33 0; }                             #sidebar .content .follow a.fb:hover {                                background-position: 0 -33; } 

on background-position properties need set value type wanting, px, em, etc. css understands 0 need more specific other values.

#sidebar .content .follow a.twit {     width: 32px; background-position: -33px 0; } #sidebar .content .follow a.fb:hover {     background-position: 0 -33px; }