表单数据未发送到php文件

Question

我在模态容器中有以下模态主体div，我只是想将输入发送到php文件。我知道它到达了文件，因为我放置了

<?php

    var_dump( $_POST);
?>

在php文件中，但打印了一个空数组。我正在使用帖子，我有一个提交按钮，所以我很困惑为什么不发送数据。有任何想法吗？

          <div class="modal-body mx-4">
                            <!--Body-->
                            <form id = "signupForm" action = "../Backend/signup.php" method= "post">
                                <div class="md-form pb-3">
                                  <input type="text" id="Form-email1" class="form-control validate">
                                  <label data-error="wrong" data-success="right" for="Form-email1"> Your username </label>
                                </div>

                                <div class="md-form pb-3">
                                  <input type="email" id="Form-username" class="form-control validate">
                                  <label data-error="wrong" data-success="right" for="Form-username"> Your email </label>
                                </div>

                                <div class="md-form pb-3">
                                  <input type="password" id="Form-pass1" class="form-control validate">
                                  <label data-error="wrong" data-success="right" for="Form-pass1">Your password</label>
                                </div>

                                 <div class="md-form pb-3">
                                  <input type="password" id="Form-pass2" class="form-control validate">
                                  <label data-error="wrong" data-success="right" for="Form-pass2">Reenter your password</label>
                                </div>

                                <div class="text-center mb-3">
                                  <button type="submit" class="btn blue-gradient btn-block btn-rounded z-depth-1a">Sign up</button>
                                </div>
                            </form>