Adding glyphicon to asp.net button using bootstrap

I'm new to bootstrap/asp.net so I must be doing something wrong. All I want is a glyphicon from bootstrap to show up next to my button. As I understand, I cannot use asp:Button, but must use LinkButton.

Code:

<form id="defaultform" runat="server">
 
<div class="container">
 <asp:LinkButton ID="ButtonGetProduct" 
            runat="server" 
            CssClass="btn btn-primary btn-lg"    
            OnClick="ButtonGetProductName_Click">
            <span class="glyphicon glyphicon-barcode"></span>Register
            </asp:LinkButton>

</div>
</form>