title: ImageButton doesn't shows the image
body: <p>I have a problem running with the ImageButton. It does not show the image of the drawable folder, it shows a small gray rectangle.</p>
  
  <p>Demomento I put only the code of the layout of the activity because by clicking on the rectangle that comes out if it does the action.</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto"
      xmlns:tools="http://schemas.android.com/tools"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      tools:context="mdl.acp.Menu"&gt;
  
  
          &lt;Spinner
                      android:id="@+id/numeroGru"
                      android:layout_width="240dp"
                      android:layout_height="25dp"
                      android:layout_alignStart="@+id/textView6"
                      android:layout_below="@+id/textView6"
                      android:layout_marginLeft="35dp"
                      android:layout_marginTop="25dp"
                      tools:layout_editor_absoluteX="82dp"
                      tools:layout_editor_absoluteY="161dp" /&gt;
  
          &lt;TextView
              android:id="@+id/textView7"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:layout_alignStart="@+id/textView6"
              android:layout_below="@+id/numeroGru"
              android:layout_marginTop="46dp"
              android:text="@string/seleccionaDtAct"
              android:textColor="@color/colorPrimary"
              android:textSize="18sp"
              android:textStyle="bold"
              tools:layout_editor_absoluteX="16dp"
              tools:layout_editor_absoluteY="251dp" /&gt;
  
                  &lt;Spinner
                      android:id="@+id/deporte"
                      android:layout_width="240dp"
                      android:layout_height="25dp"
                      android:layout_alignStart="@+id/textView7"
                      android:layout_below="@+id/textView7"
                      android:layout_marginLeft="35dp"
                      android:layout_marginTop="25dp"
                      tools:layout_editor_absoluteX="25dp"
                      tools:layout_editor_absoluteY="338dp"/&gt;
  
          &lt;TextView
              android:id="@+id/textView6"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:layout_alignParentStart="true"
              android:layout_below="@+id/relativeLayout"
              android:layout_marginStart="28dp"
              android:layout_marginTop="23dp"
              android:text="@string/seleccionaAct"
              android:textColor="@color/colorPrimary"
              android:textSize="18sp"
              android:textStyle="bold"
              tools:layout_editor_absoluteX="16dp"
              tools:layout_editor_absoluteY="84dp" /&gt;
  
          &lt;RelativeLayout
              android:id="@+id/relativeLayout"
              android:layout_width="wrap_content"
              android:layout_height="50dp"
              android:layout_alignParentStart="true"
              android:layout_alignParentTop="true"
              android:background="@color/colorPrimaryDark"
              android:layout_alignParentEnd="true"&gt;
  
                  &lt;TextView
                      android:id="@+id/textView8"
                      android:layout_width="wrap_content"
                      android:layout_height="wrap_content"
                      android:layout_centerHorizontal="true"
                      android:layout_centerVertical="true"
                      android:text="@string/nuevoAct"
                      android:textAlignment="center"
                      android:textColor="@android:color/white"
                      android:textSize="30sp"
                      android:textStyle="bold"
                      tools:text="@string/nuevoAct" /&gt;
          &lt;/RelativeLayout&gt;
  
          &lt;ImageButton
              android:id="@+id/imageButton"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:layout_alignParentBottom="true"
              android:layout_centerHorizontal="true"
              android:layout_marginBottom="40dp"
              android:elevation="0dp"
              app:srcCompat="@drawable/btnsig" /&gt;
  
  &lt;/RelativeLayout&gt;
  </code></pre>
  
  <p>The image is a png file whose dimesiones are 80x80 (32 bit color) 5.1k.
  I do not know if the problem will have to do with some attribute of the layout of width or height that has as value match parent.</p>
  
  <p>Thanks.</p>