php mysql表单提交后转到空白页面

Question

也许有人可以帮助我看到我正在犯的错误。这是一个非常简单的形式，我无法弄清楚为什么它没有正确提交。

数据库似乎连接得很好（它在config.php文件中定义），因为有几个表单项从数据库中提取。有什么想法吗？

非常感谢。

<?php

if (isset($_POST['submit']) && $_POST['submit'] == 'createAccount') {
    // Create the new contact
    $name = $mysqli->real_escape_string($_POST['name']);
    $phone = $mysqli->real_escape_string($_POST['phone']);
    $email = $mysqli->real_escape_string($_POST['email']);


    $stmt = $mysqli->prepare("
                        INSERT INTO
                            providers(
                                name,
                                phone,
                                email                               
                            ) VALUES (
                                ?,
                                ?,
                                ?
                            )");
    $stmt->bind_param('sss',
        $name,
        $phone,
        $email
    );
    $stmt->execute();
}

?>
<div class="container">
    <div class="content">
        <?php echo mysql_error() ?>
        <p>
            SEARCH FOR A CONTACT
        </p>
    </div>

    <div class="content">


        <p>
            ADD A CONTACT
            <form action="" method="post">
                <div class="modal-body">
                    <div class="row">
                        <div class="col-md-6">
                            <div class="form-group">
                                <label for="usersName">Contact Name</label>
                                <input type="text" class="form-control" name="name" />
                                <span class="help-block">Company or Person's Name</span>
                            </div>
                        </div>
                        <div class="col-md-6">
                            <div class="form-group">
                                <label for="usersEmail">Phone Number</label>
                                <input type="text" class="form-control" name="phone" />
                                <span class="help-block">Please provide contact's phone number.</span>
                            </div>
                        </div>
                    </div>

                    <div class="row">
                        <div class="col-md-6">
                            <div class="form-group">
                                <label for="text">Address</label>
                                <input type="text" class="form-control"  name="address" />
                            </div>
                        </div>
                        <div class="col-md-6">
                            <div class="form-group">
                                <label for="city">City</label>
                                <input type="text" class="form-control" name="city" />

                                <label for="state">State</label>
                                <input type="text" class="form-control" name="state" />

                                <label for="zip">Zip Code</label>
                                <input type="zip" class="form-control" name="zip" />
                            </div>
                        </div>
                    </div>
<p>Please provide the installations this provider is close to, starting with the closest. You do not need to provide more than one.</p>
                    <div class="row">

                        <div class="col-md-6">
                            <div class="form-group">
                                <label for="text">Installation 1</label>
                                <?php
                                 $result = mysqli_query($mysqli,"SELECT * FROM installations ORDER BY name");
                                 echo '<select name="installation_id" class="btn-select">';
                                 echo '<option disabled selected> -- select an option -- </option>';
                                 while($row = mysqli_fetch_array($result)) { ?>
                                    <option value="<?=$row['id']?>" > <? echo $row['name'] ?></option>
                                <?php  }
                                 echo '</select>';
                                ?>
                            </div>
                        </div>
                        <div class="col-md-6">
                            <div class="form-group">
                                <label for="text">Installation 2</label>
                                <?php
                                 $result = mysqli_query($mysqli,"SELECT * FROM installations ORDER BY name");
                                 echo '<select name="installation_id2" class="btn-select">';
                                 echo '<option disabled selected> -- select an option -- </option>';
                                 while($row = mysqli_fetch_array($result)) { ?>
                                    <option value="<?=$row['id']?>"> <? echo $row['name'] ?></option>
                                <?php  }
                                 echo '</select>';

                                ?>
                            </div>
                        </div>
                    </div>
                    <p>Please choose a provider type for this contact. Contacts can often provide more than one service, please choose all that fit this contact.</p>

                    <div class="row">
                        <div class="col-md-4">
                            <div class="form-group">
                                <label for="text">Provider Type</label>
                                <?php
                                 $result = mysqli_query($mysqli,"SELECT * FROM provider_type ORDER BY name");
                                 echo '<select name="provider_type1" class="btn-select">';
                                 echo '<option disabled selected> -- select an option -- </option>';
                                 while($row = mysqli_fetch_array($result)) { ?>
                                    <option value="<?=$row['id']?>"> <? echo $row['name'] ?></option>
                                <?php  }
                                 echo '</select>';

                                ?>
                            </div>
                        </div>
                        <div class="col-md-4">



                </div>

                    <button type="input" name="submit" value="createAccount" class="btn btn-success btn-icon"><i class="fa fa-check-square-o"></i> Create Contact</button>
                    <button type="button" class="btn btn-warning btn-icon" data-dismiss="modal"><i class="fa fa-times-circle"></i> Cancel</button>

            </form>
        </p>
    </div>