CSS Sprite for a href not initially showing up -

i'm trying use css sprite on anchor tags. however, when load page, should "initial" icon doesn't show up!! ideas? double checked image paths , indeed correct. i'm not sure if coordinates background position 100% correct, figured can tweak once icon show up! thanks!

html:

 <div id="social"> <a href="https://www.behance.net/lb155edc6" target="_blank" class="button"></a> </div> 

css:

#social a.button{ width:150px; height:150px; display:block; background-image:url('images/icons/behancesprite.png'); background-repeat:no-repeat; background-position:0 0;  } #social a.button:hover{ background-position: 0 -266px; }