PHP not writing data in MYSQL - php

Question

This is a school project and this particular page is to register a new user it does not display errors but it does not fill the MYSQL data base the connection for the database is in another page and I used the require function functions.php is where I am writing the connection function please help :(
<?php
include_once("menu.php");
?>
<form action="login.php" method="POST">
<?php
if ((isset($_POST['username']))&& (isset($_POST['password'])) && (isset($_POST['password2'])) && (isset($_POST['email'])))
{
$username = $_POST['username'];
$password = $_POST['password'];
$password2 = $_POST['password2'];
$email = $_POST['email'];
if ($password == $password2)
{
require_once("functions.php");
$connection = connectToMySQL();
$Query = "SELECT count(*) FROM tbl_users WHERE username='$username'";
$Result = mysqli_query($connection,$Query)
or die("Error in the query :". mysqli_error($connection));
$row = mysqli_fetch_row($Result);
$counter = $row[0];
if ($counter > 0)
{
echo "Username alredy exsist with the movie assosiation website<br/>";
echo "<input type=\"submit\" class=\"button\" value=\"Back\"/>";
}
else
{
$insertQuery = "INSERT INTO 'tbl_users'(username,password,email,role) VALUES ('$username',sha1('$password'),'$email','registered')";
$insertResult = mysqli_query($connection,$insertQuery)
or die("Error in the query :". mysqli_error($connection));
echo "account created !! <br />";
echo "<input type=\"button\" class=\"button\" value=\"Log In\" onclick=\"location.href='login.php'\"> ";
}
}
}
else
{
?>
<label>
<span>Username:</span>
<input id="username" type="text" name="username" placeholder="enter your Username" required />
</label></br>
<label>
<span>Password</span>
<input id="password" type="password" name="password" placeholder="enter your Password" required />
</label></br>
<label>
<span>Re-Enter Password</span>
<input id="password2" type="password" name="password2" placeholder="re-enter your Password" required />
</label></br>
<label>
<span>Email</span>
<input id="email" type="email" name="email" placeholder="enter email" required />
</label></br>
<label>
<span> </span>
<input id="submit" class="button" type="submit" name="submit" value="Submit"/>
</label>
</form>
<?php
}
?>
<?php
require_once("footer.php")
?>

Answer 1

remove single quote from your table name
try this
$insertQuery = "INSERT INTO `tbl_users`(username,password,email,role) VALUES ('$username',sha1('$password'),'$email','registered')";
instead of
$insertQuery = "INSERT INTO 'tbl_users'(username,password,email,role) VALUES ('$username',sha1('$password'),'$email','registered')";

Answer 2

Error in your sql statement.
Try this.
$insertQuery = "INSERT INTO tbl_users (username,password,email,role) VALUES ('{$username}',sha1('{$password}'),'{$email}','registered')";
or this
$insertQuery = "INSERT INTO tbl_users (username,password,email,role) VALUES ('".$username."',sha1('".$password."'),'".$email."','registered')";