Icono dentro de un boton

[BekoxD]

Hola estoy haciendo unos botones para Votación pero tengo una duda sobre poner un icono dentro del boton enlace.
Mi código es esto:

Código:

.valoracion a.positivo {background:#00A256;filter:progid:DXImageTransform.Microsoft.gradient(startColorstr='#00A256', endColorstr='#498449');
	background-image:-ms-linear-gradient(top left, #00A256 #00A256, #00A256 #498449);
	background-image:-webkit-gradient(linear, 50% 0%, 50% 100%, color-stop(0%, #00A256), color-stop(25%, #00A256), color-stop(50%, #00A256), color-stop(75%, #00A256), color-stop(100%, #498449));
	background-image:-webkit-linear-gradient(#00A256, #00A256, #00A256, #00A256, #498449);
	background-image:-moz-linear-gradient(#00A256, #00A256, #00A256, #00A256, #498449);
	background-image:-o-linear-gradient(#00A256, #00A256, #00A256, #00A256, #498449);
	background-image:linear-gradient(#00A256, #00A256, #00A256, #00A256, #498449);
	border-color:#00A256 #2e522e #2e522e #00A256;
    border-radius: 2px;
    border-style: solid;
   text-indent:-9999px;
    border-width: 1px;
    color: rgb(255, 255, 255);
    font-weight: bold;
    height: auto;
    margin-right: 3px;
    padding: 8px 10px;
    position: relative;
    text-align: center;
    text-decoration: none;
    width: 23px;
}
.valoracion  a.positivo:hover {
    filter:progid:DXImageTransform.Microsoft.gradient(startColorstr='#498449', endColorstr='#376337');background-image:-ms-linear-gradient(top left, #498449 #498449, #498449 #376337);background-image:-webkit-gradient(linear, 50% 0%, 50% 100%, color-stop(0%, #498449), color-stop(25%, #498449), color-stop(50%, #498449), color-stop(75%, #498449), color-stop(100%, #376337));background-image:-webkit-linear-gradient(#498449, #498449, #498449, #498449, #376337);background-image:-moz-linear-gradient(#498449, #498449, #498449, #498449, #376337);background-image:-o-linear-gradient(#498449, #498449, #498449, #498449, #376337);background-image:linear-gradient(#498449, #498449, #498449, #498449, #376337);border-color:#376337 #539453 #539453 #376337
}

Código HTML:

<a class="positivo" href="javascript:void(0);"> Sí*</a> 

mi icono de test es esto http://imageshack.com/a/img30/2287/gg9v.png
eh intentado las cosas abituales como ponerle

Código:

background:#00A256 url("http://imageshack.com/a/img30/2287/gg9v.png") no-repeat scroll 0% 0%;

pero nada

Haber si por favor me echan una mano.
Saludos