if（isset（$ _ POST ['submit']）不发布表单数据

Question

我的表单数据没有发布，因为某些原因我甚至无法进入第一个if语句。我一直在寻找，似乎找不到符合我问题的人的答案。

<?php
    $pagetitle = "Registration Form";
    require "header.php";

    //NEEDED VARIABLES & INCLUDES
    //$errormsg = "";
    $fnameError ="";
    $lnameError = '';
    $usrnameError = '';
    $emailError = '';
    $pwdError='';
    //$valid = true;

    if(isset($_POST['submit'])&& !empty($_POST['submit']))
    {
        echo 'here';
        /* ****************************************************************************
           CREATE NEW VARS TO STORE USER DATA & SANITIZE DATA FROM USER.
           ************************************************************************* */
        $formfield['fname'] = trim(strtolower($_POST['first']));
        $formfield['usrname'] = trim(strtolower($_POST['uname']));
        $formfield['pwd'] = trim($_POST['pwd']); //we never force a lowercase password
        $formfield['pwd2'] = trim($_POST['pwd2']); //we never force a lowercase password
        //REGEX Validation
        if(empty($_POST['fname']))
        {
            $fnameError = "You must enter a first name.";
            $valid = false;
        }
        elseif((!preg_match("/[\w\s\-]+/", $_POST['first_name']) || !preg_match("/^[a-zA-Z]/", $_POST['fname'])))
        {
            $fnameError = "Invalid first name.";
            $valid = false;
        }
        if(empty($_POST['lname']))
        {
            $lnameError = 'You must enter a last name';
            $valid = false;
        }
        elseif(!preg_match("/[\w\s\-]+/", $_POST['lname']) || !preg_match("/^[a-zA-Z]/", $_POST['lname']))
        {
            $lnameError = "Invalid last name.";
            $valid = false;
        }

        if(empty($_POST['email']))
        {
            $emailError = 'You must enter an email.';
            $valid = false;
        }
        elseif(!preg_match("/@/", $_POST['email']))
        {
            $emailError = 'Invalid email';
            $valid = false;
        }

        if(empty($_POST['pwd']))
        {
            $pwdError = 'You must enter a password.';
            $valid = false;
        }
        elseif($_POST['pwd'] != $_POST['pwd2'])
        {
            $pwdError = "Passwords did not match.";
            $valid = false;
        }
        elseif(!preg_match("/.{6}/", $_POST['pwd']))
        {
            $pwdError = 'Password must be longer than 6 characters.';
            $valid = false;
        }
        /* ****************************************************************************
           CHECK FOR DUPLICATE USERS
           ************************************************************************* */
        try
        {
            $sqlusers = "SELECT * FROM users WHERE usrname = :usrname";
            $stmtusers = $pdo->prepare($sqlusers);
            $stmtusers->bindValue(':usrname', $formfield['usrname']);
            $stmtusers->execute();
            $countusers = $stmtusers->rowCount();
            if ($countusers > 0)
            {
                $usrnameError = "Username already taken";
            }
        }
        catch (PDOException $e)
        {
            echo "<div class='error'><p></p>ERROR selecting users!" .$e->getMessage() . "</p></div>";
            exit();
        }

        /*  ****************************************************************************
            HASH THE PASSWORD
            **************************************************************************** */
            $securepwd = password_hash($formfield['pwd'], PASSWORD_DEFAULT);

        /*  ****************************************************************************
            CONTROL FOR ERRORS.  IF ERRORS, DISPLAY THEM.  IF NOT, CONTINUE WITH FORM PROCESSING.
            **************************************************************************** */
            try
            {
                $sql = "INSERT INTO users(id, fname, lname, pwd, email, usrname, question, questionAnswer)
                            VALUES (5,'penis',[value-3],[value-4],[value-5],[value-6],[value-7],[value-8])";
                $stmt = $pdo->prepare($sql);
                $stmt->bindvalue(':fname', $formfield['fname']);
                $stmt->bindvalue(':usrname', $formfield['usrname']);
                $stmt->bindvalue(':pwd', $securepwd);
                $stmt->execute();
                $showform=0; //hide the form
                echo "<div class='success'><p>There are no errors.  Thank you for registering.</p></div>";
            }//try
            catch(PDOException $e)
            {
                echo "<div class='error'><p>ERROR inserting data into the database!" .$e->getMessage() . "</p></div>";
                exit();
            }
        //else errors
    }//isset submit ?>

我不知道发生了什么，这是HTML代码

<div class="container">
<div class="jumbotron">
    <form method="post" action="">
        <div class="form-group">
            <label for="fname">First Name: </label><span style="font-size: small; color: red"><?php echo $fnameError?></span>
            <input type="text" class="form-control" id="fname" name="fname">
        </div>
        <div>
            <label for="lname">Last Name: </label><span style="font-size: small; color: red"><?php echo $lnameError?></span>
            <input type="text" class="form-control" id="lname" name="lname">
        </div>
        <div>
            <label for="email">Email: </label><span style="font-size: small; color: red"><?php echo $emailError?></span>
            <input type="email" class="form-control" id="email" name="email">
        </div>
        <div>
            <label for="usrname">Username: </label><span style="font-size: small; color: red"><?php echo $usrnameError?></span>
            <input type="text" class="form-control" id="usrname" name="usrname">
        </div>
        <div>
            <label for="question">Security Question: </label>
            <input type="text" class="form-control" id="question" name="question" >
            <input type="text" class="form-control" id="questionAnswer" name="questionAnswer">
        </div>
        <label for="pwd">Password: </label><?php echo $pwdError?>
        <input type="password" class="form-control" id="pwd" name="pwd">
        <label for="pwd2">Confirm: </label><?php echo $pwdError?>
        <input type="password" class="form-control" id="pwd2" name="pwd2">
        <button type="submit" class="btn-default" value="Submit" name="Submit">Register</button>
    </form>
</div>