Because the drawable that's not showing up is itself inside a RelativeLayout, you need to put some position attributes in the cadremenu layout so that Android knows where to place it. For example, try:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="monteil.gaming.hundredious.MainActivity" >
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="@drawable/fondipad"
android:contentDescription="@string/FondDesc"
/>
<RelativeLayout
android:layout_height="300dp"
android:layout_width="fill_parent"
**android:layout_alignParentTop="true"**
android:background="@drawable/cadremenu">
</RelativeLayout>
</RelativeLayout>