JavaScript CSS styling in IE

JavaScript CSS styling not working in IE, it is working in Chrome and Mozilla.

This is my code:

document.ready=function() {
        var val = document.getElementById("registration_select").value;
        if(val =="Relay - Ultra, Standard and Sprint distances (Men / Women/ Mixed) - open to all Age-Groups & Juniors above 16"){            
        document.getElementById("register_right").style.display="block";
        }
        else{            
        document.getElementById("register_right").style.display="none";
        }

 registration_select.onchange=function(){
        var val = document.getElementById("registration_select").value;
        if(val =="Relay - Ultra, Standard and Sprint distances (Men / Women/ Mixed) - open to all Age-Groups & Juniors above 16"){            
        document.getElementById("register_right").style.display="block";
        }
        else{            
        document.getElementById("register_right").style.display="none";
        }
     }
};

This is my HTML

<select id="registration_select" name="Category">
<option value="category1">category1</option>
<option value="Relay - Ultra, Standard and Sprint distances (Men / Women/ Mixed) - open to all Age-Groups & Juniors above 16">Relay - Ultra, Standard and Sprint distances (Men / Women/ Mixed) - open to all Age-Groups & Juniors above 16</option>
</select>

<div id="register_right">

<h3>Team Mate Profile</h3>

</div>

And this is my CSS

#register_right{float:right;  display:none; width:49%;}

Please Help.

Answer

Try this

 jQuery(function($) {
        var val = document.getElementById("registration_select").value;

            if(val =="Relay - Ultra, Standard and Sprint distances (Men / Women/ Mixed) - open to all Age-Groups & Juniors above 16"){            
                document.getElementById("register_right").style.display="block";
            }
            else{            
                document.getElementById("register_right").style.display="none";
            }

            document.getElementById("registration_select").onchange=function(){
                var val = document.getElementById("registration_select").value;
                if(val =="Relay - Ultra, Standard and Sprint distances (Men / Women/ Mixed) - open to all Age-Groups & Juniors above 16"){            
                    document.getElementById("register_right").style.display="block";
                }
                else{            
                    document.getElementById("register_right").style.display="none";
                }
            }

    });