求TP大神帮小弟我看看，为什么不能验证登陆

<!-- 弹出登陆框 --><br /><div class="theme-popover"><br />     <div class="theme-poptit"><br />          <a href="javascript:;" title="关闭" class="close">×</a><br />          <h3 style="font-size:20px;">会员登陆</h3><br />     </div><br />     <div class="theme-popbod dform"><br />           <form class="theme-signin" name="loginform"><br />                <ol><br />                     <li><strong>用户名：</strong><input class="ipt" type="text" name="username"  size="20" placeholder="手机/邮箱/用户名"/></li><br />                     <li><strong>密码：</strong><input class="ipt" type="password" name="password" size="20" placeholder="请输入你的密码"/></li><br />                     <li><input  id="btnEnter" class="btn btn-primary" type="submit" name="submit" value="登 录 " /></li><br />                     <li style="margin-left:30%;margin-top:-12%;"><a href="">忘记密码  ?</a></li><br />                     <li style="margin-left:-20%;margin-top:12%;"><input type="checkbox">记住账号</li><br />                     <li><br/><div id="datainfo"></div></li><br />                </ol><br />           </form><br />     </div><br /></div>[code=javascript]<script type="text/javascript"><br />	$(function(){<br />		//提交表单<br />		$('#btnEnter').click(function()<br />		{<br />			var username=$('input[name="username"]').val();<br />			var password=$('input[name="password"]').val();<br />			//alert(password);<br /><br />			$.get('__URL__/doLogin',{'username':username,'password':password},function(data)<br />			{<br />				if(data=='验证成功')<br />				{<br />					window.location='__APP__/index/index';<br />				}<br />				else if(data=='验证失败')<br />				{<br />					$('#datainfo').html("管理员登录失败.");<br />				}<br />			});<br /><br />			$('input[class="boxcontent"]').blur(function()<br />			{<br />				$('#datainfo').html("");<br />			});<br />		});<br />	});<br /></script>

 //登陆验证<br />   public function doLogin()<br />   {<br />   	$username=$_GET['username'];<br />   	$password=$_GET['password'];<br />   	$user=M('member');<br />   	$where['username']=$username;<br />   	$where['password']=md5($password);<br />   	$count=$user->where($where)->count();<br />   	if($count)<br />   	{<br />   		$_SESSION['username']=$username;<br />   		echo '验证成功';<br />   	}<br />   	else<br />   	{<br />   		echo '验证失败';<br />   	}<br />   }