Fill again when want to use button

fragment_face_book_screen.xml

<?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        >

        <LinearLayout
            android:orientation="vertical"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_alignParentTop="true"
            android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true"
            android:weightSum="1">
            <LinearLayout
                android:orientation="horizontal"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:id="@+id/FblinearLayout">
                <RelativeLayout
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:padding="10dp">


                    <ImageButton
                        android:src="@drawable/login_with_facebook"
                        android:background="@android:color/transparent"
                        android:id="@+id/AuthButton"
                        android:scaleType="center"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:layout_alignParentRight="true"
                        android:layout_alignParentEnd="true"
                        android:layout_alignParentLeft="true"
                        android:layout_alignParentStart="true"

                         />
                </RelativeLayout>
            </LinearLayout>




            <LinearLayout
                android:orientation="horizontal"
                android:layout_width="match_parent"
                android:layout_height="416dp"
                android:layout_gravity="center_horizontal"
                android:weightSum="1">

                <RelativeLayout
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"

                    >

                    <ListView
                        android:layout_width="match_parent"
                        android:layout_height="match_parent"
                        android:id="@+id/FblistView"
                         />
                </RelativeLayout>
            </LinearLayout>
            <LinearLayout
                android:orientation="horizontal"
                android:layout_width="match_parent"
                android:layout_height="match_parent">
                <Button
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    android:layout_marginLeft="45dp"
                    android:layout_marginRight="45dp"
                    android:text="Add"
                    android:id="@+id/add"
                    android:background="#ff242424"
                    android:textColor="#ffffffff" />

            </LinearLayout>

        </LinearLayout>

    </RelativeLayout>