Android : How to Add to Activity under OnClick?

Hello, I'm building an app which have three button to open each activity from the Main Activity. the first activity (Inbox Activity) opens up fine but everytime i press the MMS button to open MMS Activity, the app crashes then opens up the MMS Activity. the same thing happens when i press the third button to open activity but even after pressing the third activity it opens the MMS activity not the third activity (SMS Activity). Any idea how to fix this issue?

@Override
public void onClick(View v) {

    Intent intent = new Intent(this, InboxActivity.class);
    startActivity(intent);

    Intent in = new Intent(this, MMSActivity.class);
    startActivity(in);

}

}