I'm using struts2,i'm asking about the radio button validation

my form

< s: form action="creatingcv" method="post" onsubmit="return valider()" id="frmSaisie">

< s:radio name="cv.gender" label="Gender" list="{'Male','Female'}" id="Gender"/>

< /s:form>

i used this javascript code but it didnt work

function valider(){

frm=document.forms['frmSaisie'];

if (frm.elements['Gender'].value != "") {
return true;

                } 
             else { 
                        alert("Please choose your gender"); 
            return false;

} }

i tested with other components this javascript code and it worked well but with this one it does nothing

i tested too (frm.elements['Gender'].checked != false) but it returns nothing..

if Someone have and Idea Please Help..thxx