Read File From LoginModule Running Under Security Manager

I have followed the Java tutorial on JAAS Authentication and Authorization. All the sample code in the tutorials works fine also when running under a security manager. Now I am trying to modify the LoginModule class, so that it uses a password file to look up users and passwords, but as soon as I try to run the code under a security manager, I get a Security Exception. I suppose it has something to do with the code havent been granted any access to read the password file? So I tried to add this to the policy file:

grant codebase "file:./sample/module/-" {
permission java.io.FilePermission "sample/module/passwords.txt", "read";
};

It didn't do any difference. why I get this Security Exception?

The only difference from my code to the tutorial code, is that I have added the lines:

Scanner scanner = null;
try {
scanner = new Scanner(new File("src/sample/module/passwords.txt"));
} catch (FileNotFoundException e) {
e.printStackTrace();
}

to the login() method of the SampleLoginModule class...