Не обновлять базу данных SQL

По какой-то причине мой код не обновляет базу данных mySQL, но он не сообщает о каких-либо ошибках.

register.php (форма)

<form class="register_form" action="action.php?do=register" method="post"> Team Name*: <input type="text" name="teamname" required /> Team Region*: <input type="text" name="teamregion" maxlength="4" required /> Team Leader*: <input type="text" name="teamleader" maxlength="16" required /> Team Members: <input type="text" name="teammembers" /> <input name="register_submit" type="submit" value="Register" /> </form> 

action.php

  <?php $con=mysqli_connect("192.185.#.###","########_reg","#######","#########"); if (mysqli_connect_errno()) {echo "Failed to connect to MySQL: " . mysqli_connect_error();} $action = $_GET['do']; if($action=="register") { $teamname = $_POST["teamname"]; $teamregion = $_POST["teamregion"]; $teamleader = $_POST["teamleader"]; $teammembers = $_POST["teammembers"]; $result = mysqli_query($con, "INSERT INTO teams (teamname, region, teamleader, teammembers, wins, loses) VALUES (" . $teamname . "," . $teamregion . "," . $teamleader . "," . $teammembers . ",0,0);"); } ?> 

Любые идеи, почему это работает неправильно?