window.location.href失效

function sampleQuery(txt,event){            var name=document.getElementById(txt).value.replace(/^\s*/,"").replace(/\s*$/,"");            if(name==""||name==null)                alert("请输入昵称");            else{                window.location.href="friend.aspx?name="+escape(name)+"&sex=2";                if(window.event)                   window.event.returnValue = false;                else                    event.preventDefault();//for firefox            }        }        function KeyDown(event){            var keynum;            if(window.event) // IE            {              keynum = window.event.keyCode            }            else if(event.which) // Netscape/Firefox/Opera            {              keynum = event.which            }            if(keynum==13)                sampleQuery('TxtName',event);        }一个input 当回车的时候我会引用一个函数 那个函数中有 window.location.href 但是不跳转，当改成那段代码后就OK了