Android : Android: Negative margin top does not work

I create RelativeLayout and use 2 images

I use margin-top:-1; but not work

XML code :

<LinearLayout
                            android:layout_width="0dp"
                            android:layout_height="wrap_content"
                            android:layout_marginLeft="6dp"
                            android:layout_marginTop="6dp"
                            android:layout_weight="0.5"
                            android:background="@drawable/bg_white_new"
                            android:orientation="vertical"
                            android:padding="3dp" >

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

                                <ImageView
                                    android:id="@+id/ImageView05"
                                    android:layout_width="wrap_content"
                                    android:layout_height="wrap_content"
                                    android:adjustViewBounds="true"
                                    android:scaleType="centerCrop"
                                    android:src="@drawable/post" />

                                <ImageView
                                    android:id="@+id/imageView5"
                                    android:layout_width="wrap_content"
                                    android:layout_height="wrap_content"
                                    android:src="@drawable/like" android:layout_marginTop="-1dp"/>

                            </RelativeLayout>

                        </LinearLayout>