Hi there I'm totally new to Android development and I'm working in my android application my application includes a forum where users can post, comment and have their discussion there.... So I'm working in the interface but I get error when I click on the button I directs me to the signup page can somebody please help me with this error

this is the code of the mainuserinterface.java for the mainuserinterface.xml file where the button resides. and the signupform.class is the java file for the next activity triggered when the button is clicked

the error I receive is the application is unexpectedly stopped.. Hope I make it clear for you guys

package com.mohammed.watzIslam;


import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class mainuserinterface extends Activity  {


@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.mainuserinterface);

// this is the button where I receive errors when I click 
Button forum = (Button) findViewById(R.id.next); 

forum.setOnClickListener(new View.OnClickListener() {
    public void onClick(View view){
        Intent myIntent = new Intent (view.getContext(), signupform.class);
        startActivityForResult (myIntent, 0);

    }
});

 //these two button still not directing to any next activity yet
Button button1 = (Button) findViewById(R.id.next); 

forum.setOnClickListener(new View.OnClickListener() {
    public void onClick(View view){
        Intent myIntent1 = new Intent (view.getContext(), signupform.class);
        startActivityForResult (myIntent1, 0);

    }
});
Button button2 = (Button) findViewById(R.id.next); 

forum.setOnClickListener(new View.OnClickListener() {
    public void onClick(View view){
        Intent myIntent2 = new Intent (view.getContext(), signupform.class);
        startActivityForResult (myIntent2, 0);

    }
});
}
}