App isn't installed

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_fun_facts);

    //Declare our vew variables and assign the Views from the layout file.
   TextView factLabel = (TextView) findViewById(R.id.fun_facts);
   Button showFactButton=(Button) findViewById(R.id.ShowFactButton);
    View.OnClickListener listener = new View.OnClickListener() {
        @Override
        public void onClick(View view) {
          //The button was clicked, so update the fact label with a new fact

        }
    };
    showFactButton.setOnClickListener(listener);
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_fan_facts, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

<TextView android:text="Did you know?" android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAllCaps="false"
    android:textSize="24sp"
    android:textColor="#80ffffff" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Eleni is happy every day!"
    android:id="@+id/FactsTextView"
    android:layout_centerVertical="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:textSize="24sp"
    android:textColor="@android:color/white" />

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Show Another Fun Fact"
    android:id="@+id/ShowFactButton"
    android:layout_alignParentBottom="true"
    android:layout_alignRight="@+id/FactsTextView"
    android:layout_alignEnd="@+id/FactsTextView"
    android:background="@android:color/white" />