android - Add imageView to coordinatorLayout -

here coordinator layout. ok, can see everything.

but can't see imageview. in code initializing imageview correctly , have object. need image view in center of screen.

if change imageview button see button in center of screen, if change other can´t seen element.

please how can add imageview coordinatorlayout?

this code in coordinatorlayout.

thank you.

<android.support.design.widget.coordinatorlayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" android:id="@+id/main_content" android:layout_width="match_parent" android:layout_height="match_parent" android:fitssystemwindows="true">  <imageview     android:id="@+id/status_btn"     android:layout_width="150dp"     android:layout_height="150dp"     android:layout_gravity="center"     android:background="@color/red" />  <button     android:id="@+id/delete_btn"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:text="smazat"     android:visibility="gone" />  <include     layout="@layout/panel_camera_preview"     android:layout_width="match_parent"     android:layout_height="match_parent"     app:layout_behavior="@string/appbar_scrolling_view_behavior" />  <!--height width se nastavuje dynamicky--> <linearlayout     android:id="@+id/bottom_sheet"     android:layout_width="match_parent"     android:layout_height="0dp"     android:cliptopadding="true"     app:layout_behavior="android.support.design.widget.bottomsheetbehavior">      <relativelayout         android:id="@+id/bottom_sheet_content"         android:layout_width="match_parent"         android:layout_height="match_parent"         android:orientation="vertical">          <linearlayout             android:id="@+id/header_vg"             android:layout_width="match_parent"             android:layout_height="@dimen/vision_bottom_sheet_header_height"             android:layout_alignparenttop="true"             android:background="@color/gray_header_vision"             android:gravity="center">              <textview                 android:id="@+id/header_tv"                 android:layout_width="match_parent"                 android:layout_height="wrap_content"                 android:gravity="center_horizontal"                 android:textcolor="@color/white"                 android:textsize="16sp" />          </linearlayout>          <android.support.v7.widget.recyclerview             android:id="@+id/vision_list"             android:layout_width="match_parent"             android:layout_height="match_parent"             android:layout_below="@+id/header_vg"             android:background="@color/white"             android:scrollbars="vertical"             android:visibility="gone" />          <include             android:id="@+id/empty_vg"             layout="@layout/panel_vision_tutorial"             android:layout_width="match_parent"             android:layout_height="@dimen/vision_bottom_sheet_item_height"             android:layout_below="@+id/header_vg" />      </relativelayout>  </linearlayout>  </android.support.design.widget.coordinatorlayout> 

here panel_camera_preview:

<my_package.camerasourcepreview android:id="@+id/camera_preview" xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:background="@android:color/darker_gray">  <my_package.graphicoverlay     android:id="@+id/face_overlay"     android:layout_width="match_parent"     android:layout_height="match_parent"/>  </my_package.camerasourcepreview> 

coordinatorlayout framelayout, last view in order overlays previous ones. imageview results not visible because covered panel_camera_preview, while button results visible, if running on lollipop or greater, cause default elevation (2dp).