只要在xml布局中加入FloathingActionButton导致app运行崩溃

我的运行环境compileSdkVersion 24
buildToolsVersion "24.0.2"
我导入的是compile 'com.android.support:design:24.2.0'。
布局中是这样写的
android:src="@drawable/btn_bottom_back"
android:alpha="0.9"
android:layout_margin="20dp"
android:backgroundTint="#111"
android:layout_width="45dp"
android:layout_height="45dp" /> 我觉得没有任何问题。
一跳转到activity就崩溃。
注册：
报错内容为：
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.wenny.themost/com.wenny.themost.activity.JingXuanArticleActivity}: android.view.InflateException: Binary XML file line #98: Binary XML file line #98: Error inflating class android.support.design.widget.FloatingActionButton

             Caused by: android.view.InflateException: Binary XML file line #98: Binary XML file line #98: Error inflating class android.support.design.widget.FloatingActionButton

             Caused by: android.view.InflateException: Binary XML file line #98: Error inflating class android.support.design.widget.FloatingActionButton

             Caused by: java.lang.reflect.InvocationTargetException
                                                                   at java.lang.reflect.Constructor.newInstance(Native Method)

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.graphics.drawable.Drawable android.graphics.drawable.Drawable$ConstantState.newDrawable()' on a null object reference

已解决。。。。属性写错了。backgroundTint是app：backgroundTint，不是android：backgroundTint

android:id="@+id/shoucang"
android:alpha="0.9"
android:src="@drawable/shoucang"
android:backgroundTint="#fd6f32"
android:layout_width="45dp"
android:layout_height="45dp" />

android.support.design.widget.FloatingActionButton

大神们，怎么解决这个问题。。