Indeed, the button is displayed, it is just hidden by the gray banner at the bottom.
The point is that the facebook button is an iframe with a 100 something pixel height.
So this height is pushing down the other buttons. that's why we decided to put it under the product image.
The solution is to play around with css. Each button has a class, you just have to set an absolution position to the twitter and pinterest buttons, then play with the width.
Example
.hikashop_social_tw_horizontal{
position:absolute;
}
.hikashop_social_pinterest{
position: absolute;
left: 60px;
}
.hikashop_social_fb{
margin-left: 120px;
}
I didn't test this code but it should give you an idea (and it may work
). This code has to be added in System>Configuration>display to the front end css file.