show div onchange of dropdownlist value using javascript

Question

i have a dropdownlist and i want to show a div ochange event using javascript but it says object required

aspx code

<asp:DropDownList runat="server" ID="lstFilePrefix1" onchange="showTR();" >
                            <asp:ListItem Text="Prefix1" Value="Prefix1" />
                            <asp:ListItem Text="Prefix2" Value="Prefix2" />
                            <asp:ListItem Text="Prefix3" Value="Prefix3" />
                            <asp:ListItem Text="Prefix1 and Prefix2" Value="Prefix1 and Prefix2" />
                            <asp:ListItem Text="Prefix2 and Prefix3" Value="Prefix2 and Prefix3" />
                            </asp:DropDownList>

and javascript code inside .js file

function showTR() {
var dropdown = document.getElementById( "<%=lstFilePrefix1.ClientID%>" ); // Get a reference to the dropdown (select) element
var selectedItemValue = dropdown.options[ dropdown.selectedIndex ].value; // use the dropdown reference to get the selected item's value

var div2 = document.getElementById( "data" ); // Get a reference to div2

if( selectedItemValue == 'Prefix2' ) {
div2.style.dispaly= "block";// If the selectedItemValue is 'Action', show div2
} else {
div2.style.display = "none"; // Otherwise, hide div2
}
}