The login button, it does nothing.

package me.paxana.alerta;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

import com.parse.LogInCallback;
import com.parse.ParseException;
import com.parse.ParseUser;
import com.parse.SignUpCallback;

import butterknife.Bind;
import butterknife.ButterKnife;
import butterknife.OnClick;

public class LoginActivity extends AppCompatActivity {
    @Bind(R.id.usernameField) EditText mUsername;
    @Bind(R.id.passwordField) EditText mPassword;
    @Bind(R.id.loginButton) Button mLoginButton;
    @Bind(R.id.signupButton) TextView mSignupButton;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);
        ButterKnife.bind(this);

        mSignupButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(LoginActivity.this, SignupActivity.class);
                startActivity(intent);

                mLoginButton.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        String username = mUsername.getText().toString();
                        String password = mPassword.getText().toString();

                        username = username.trim();
                        password = password.trim();

                        if (username.isEmpty() || password.isEmpty()) { //if they leave a field blank give them an error
                            AlertDialog.Builder builder = new AlertDialog.Builder(LoginActivity.this);
                            builder.setMessage(R.string.Login_Error_Message)
                                    .setTitle(R.string.Login_Error_title)
                                    .setPositiveButton(android.R.string.ok, null);
                                    AlertDialog dialog = builder.create();
                            dialog.show();}
                        else { //if every field is accounted for, log in.
                    ParseUser.logInInBackground(username, password, new LogInCallback() {
                        @Override
                        public void done(ParseUser user, ParseException e) {

                            if (e == null) { //if no errors return
                                Intent intent = new Intent(LoginActivity.this, MainActivity.class); // then we logged in, start the app!
                                intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                                intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
                                startActivity(intent);} // success }
                            else {
                                AlertDialog.Builder builder = new AlertDialog.Builder(LoginActivity.this); //something went wrong logging in
                                builder.setMessage(e.getMessage())  // get a meaningful error message from parse
                                        .setTitle(R.string.Login_Error_title)
                                        .setPositiveButton(android.R.string.ok, null);
                                AlertDialog dialog = builder.create();
                                dialog.show();
                            }
                        }
                    });
                        }
                        }
                    });
            }
        });
    }
}