新密码和确认密码字段不匹配错误

Question

在这里，当我尝试注册自己时，弹出窗口显示 localhost“新密码和确认密码字段不匹配！！” 即使在输入电子邮件、电话、姓名、密码和正确密码后，它也向我显示相同的错误新密码和确认密码字段不匹配错误

我是新手，我不明白发生了什么。 请帮我！ 我该如何解决这个问题？

<?php
    //error_reporting(0);
    if(isset($_POST['signup']))
    {
        $fname=$_POST['fullname'];
        $email=$_POST['emailid']; 
        $mobile=$_POST['mobileno'];
        $password=md5($_POST['password']); 
        $sql="INSERT INTO  tblusers(FullName,EmailId,ContactNo,Password) VALUES(:fname,:email,:mobile,:password)";
        $query = $dbh->prepare($sql);
        $query->bindParam(':fname',$fname,PDO::PARAM_STR);
        $query->bindParam(':email',$email,PDO::PARAM_STR);
        $query->bindParam(':mobile',$mobile,PDO::PARAM_STR);
        $query->bindParam(':password',$password,PDO::PARAM_STR);
        $query->execute();
        $lastInsertId = $dbh->lastInsertId();
        if($lastInsertId) {
            echo "<script>alert('Registration successfull. Now you can login');</script>";
        } else {
            echo "<script>alert('Something went wrong. Please try again');</script>";
        }
    }
?>

<script>
function checkAvailability() {
    $("#loaderIcon").show();
    jQuery.ajax({
        url: "check_availability.php",
        data:'emailid='+$("#emailid").val(),
        type: "POST",
        success:function(data){
            $("#user-availability-status").html(data);
            $("#loaderIcon").hide();
        },
        error:function (){}
    });
}
</script>

<script type="text/javascript">
function valid() {
    if(document.signup.password.value!= document.signup.confirmpassword.value) {
        alert("Password and Confirm Password Field do not match  !!");
        document.signup.confirmpassword.focus();
        return false;
    }
    return true;
}
</script>

<div class="modal fade" id="signupform">
  <div class="modal-dialog" role="document">
    <div class="modal-content">
      <div class="modal-header">
        <button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">&times;</span></button>
        <h3 class="modal-title">Sign Up</h3>
      </div>
      <div class="modal-body">
        <div class="row">
          <div class="signup_wrap">
            <div class="col-md-12 col-sm-6">
              <form  method="post" name="signup" onSubmit="return valid();">
                <div class="form-group">
                  <input type="text" class="form-control" name="fullname" placeholder="Full Name" required="required">
                </div>
                      <div class="form-group">
                  <input type="text" class="form-control" name="mobileno" placeholder="Mobile Number" maxlength="10" required="required">
                </div>
                <div class="form-group">
                  <input type="email" class="form-control" name="emailid" id="emailid" onBlur="checkAvailability()" placeholder="Email Address" required="required">
                   <span id="user-availability-status" style="font-size:12px;"></span> 
                </div>
                <div class="form-group">
                  <input type="password" class="form-control" name="password" placeholder="Password" required="required">
                </div>
                <div class="form-group">
                  <input type="password" class="form-control" name="confirmpassword" placeholder="Confirm Password" required="required">
                </div>
                <div class="form-group checkbox">
                  <input type="checkbox" id="terms_agree" required="required" checked="">
                  <label for="terms_agree">I Agree with <a href="#">Terms and Conditions</a></label>
                </div>
                <div class="form-group">
                  <input type="submit" value="Sign Up" name="signup" id="submit" class="btn btn-block">
                </div>
              </form>
            </div>
            
          </div>
        </div>
      </div>
      <div class="modal-footer text-center">
        <p>Already got an account? <a href="#loginform" data-toggle="modal" data-dismiss="modal">Login Here</a></p>
      </div>
    </div>
  </div>
</div>