Look at your
greeonarange.css file located in templates/yourtemplate/css
a.readon, a.readon:hover, a.readon:visited {
-moz-background-clip:border;
-moz-background-inline-policy:continuous;
-moz-background-origin:padding;
background:transparent url(../images/greenorange/bg_read_more.png) no-repeat scroll left top;
color:#FFFFFF;
display:block;
height:29px;
line-height:29px;
margin:10px 0 0;
padding-left:30px;
width:114px;
}
You have a picture that is too smal - make it bigger and it should work:
../images/greenorange/bg_read_more.png
