ارجوا المساعدة مشكلة في كود المقارنة مع الداتا بيز

package com.grade;


import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.graphics.Color;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;


public class MyClass extends Activity {



SQLiteDatabase mydb;
private static String DBNAME = "cancer.db";
private static String TABLE = "admin";


/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.login);
Button buttonOne = (Button) findViewById(R.id.LoginButton);
buttonOne.setOnClickListener(new Button.OnClickListener() {
public void onClick(View v) {
EditText username;
EditText password;

String user_name;
String pass_word;

username = (EditText) findViewById(R.id.Username);
password = (EditText) findViewById(R.id.Password);
user_name = username.getText().toString();
pass_word = password.getText().toString();

if( validateUser(user_name, pass_word));
{
Intent goToNextActivity = new Intent(getApplicationContext(), PatientForm.class);
startActivity(goToNextActivity);
}

}
});




}



public boolean validateUser(String username, String password){


Cursor c = getReadableDatabase().rawQuery(
"SELECT * FROM " + TABLE + " WHERE "
+ username + "='" + username +"'AND "+password+"='"+password+"'" , null);
if (c.getCount()>0)
return true;
return false;
}






private SQLiteDatabase getReadableDatabase() {
// TODO Auto-generated method stub
return null;
}



public void createTable(){
try{
mydb = openOrCreateDatabase(DBNAME, Context.MODE_PRIVATE,null);
mydb.execSQL("CREATE TABLE IF NOT EXISTS "+ TABLE +" (id INTEGER PRIMARY KEY, name TEXT, password TEXT);");
mydb.close();
}catch(Exception e){
Toast.makeText(getApplicationContext(), "Error in creating table", Toast.LENGTH_LONG);
}

}
public void insertIntoTable(){
try{
mydb = openOrCreateDatabase(DBNAME, Context.MODE_PRIVATE,null);
mydb.execSQL("INSERT INTO " + TABLE + "(name, password) VALUES('admin','admin')");
mydb.execSQL("INSERT INTO " + TABLE + "(name, password) VALUES('alaa','a')");

mydb.close();
}catch(Exception e){
Toast.makeText(getApplicationContext(), "Error in inserting into table", Toast.LENGTH_LONG);
}
}




}








ارجو ان تخبروني اين المشكلة طبعا الكود هو عبارة عن صفحة دخول للبرنامج