getDatabase() is returning NullPointerException please help

Error

MineMail.jar :

Code:

package com.alta189.minemail;

import java.io.File;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Logger;

import javax.persistence.PersistenceException;

import org.bukkit.plugin.PluginDescriptionFile;
import org.bukkit.plugin.PluginManager;
import org.bukkit.plugin.java.JavaPlugin;

public class MineMail extends JavaPlugin {

    public Logger log = Logger.getLogger("Minecraft");
    public String logPrefix = "[MineMail] ";
    public String mainDir = "plugins/mainDir";

    @Override
    public void onDisable() {
        ebeansFile.delete();
    }

    @Override
    public void onEnable() {
        PluginDescriptionFile pdfFile = this.getDescription();
        PluginManager pm = getServer().getPluginManager();

        createMainDir();

        setupDatabase();
    }

    private void setupDatabase() {
        try {
            getDatabase().find(MailServer.class).findRowCount();
        } catch (PersistenceException ex) {

            installDDL();
        }
    }

     @Override
        public List<Class<?>> getDatabaseClasses() {
            List<Class<?>> list = new ArrayList<Class<?>>();
            list.add(MailServer.class);
            return list;
        }

    private void createMainDir() {
        File folderMain = new File(mainDir);

        if (!folderMain.exists()) {
            folderMain.mkdir();
        }
    }
}

MailServer.jar

Code:

package com.alta189.minemail;

import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

import com.avaje.ebean.validation.NotNull;


@Entity()
@Table(name = "MailServer")
public class MailServer {
	@Id
	private int id;
	@NotNull
	private String toWhom;
	@NotNull
	private String fromWhome;
	@NotNull
	private String message;
	@NotNull
	private Boolean read;

	public void setId(int id) {
		this.id = id;
	}

	public int getId() {
		return id;
	}

	public void setToWhom(String toWhom) {
		this.toWhom = toWhom;
	}

	public String getToWhom() {
		return toWhom;
	}

	public void setFromWhome(String fromWhome) {
		this.fromWhome = fromWhome;
	}

	public String getFromWhome() {
		return fromWhome;
	}

	public void setMessage(String message) {
		this.message = message;
	}

	public String getMessage() {
		return message;
	}

	public void setRead(Boolean read) {
		this.read = read;
	}

	public Boolean getRead() {
		return read;
	}
}

FIXED: I forgot to add database: true in plugin.yml
Oh the stupid mistakes that one can make when programming!!

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

i'm getting the same problem but i have the database: true in the plugin.yml :S