android – 渐变背景在某些设备中不起作用

我正在使用渐变drawable用于 Image内部阴影,它适用于某些设备(检入模拟器)但在某些设备中不起作用.首先我认为它将取决于api级别的设备但是今天我检查同样的事情在具有api级别“16”(即果冻豆)的平板电脑上,它也不起作用.

渐变代码(适用于所有四个边的内部阴影)：

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://scheR_732_11845@as.android.com/apk/res/android" >

    <item>
        <shape android:shape="rectangle" >
        </shape>
    </item>
    <item
        android:bottom="114dip"
        android:top="0dip">
        <shape android:shape="rectangle" >
            <gradient
                android:angle="270"
                android:endColor="#00000000"
                android:startColor="#40000000" />
        </shape>
    </item>
    <item
        android:bottom="0dip"
        android:top="114dip">
        <shape android:shape="rectangle" >
            <gradient
                android:angle="90"
                android:endColor="#00000000"
                android:startColor="#40000000" />
        </shape>
    </item>
    <item
        android:left="0dip"
        android:right="114dip">
        <shape android:shape="rectangle" >
            <gradient
                android:angle="360"
                android:endColor="#00000000"
                android:startColor="#40000000" />
        </shape>
    </item>
    <item
        android:left="114dip"
        android:right="0dip">
        <shape android:shape="rectangle" >
            <gradient
                android:angle="180"
                android:endColor="#00000000"
                android:startColor="#40000000" />
        </shape>
    </item>

</layer-list>

我的布局代码：

<FrameLayout
                android:id="@+id/about"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center_vertical"
                android:layout_weight="1"
                android:BACkground="@color/light_green" >

                <ImageView
                    android:id="@+id/home_icon_placeholder"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:src="@drawable/home_icon_placeholder" />

                <TextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_gravity="center"
                    android:drawablePadding="5dp"
                    android:drawableTop="@drawable/about_icon"
                    android:gravity="center"
                    android:text="@String/about_champions_club_btn_txt"
                    android:textColor="@android:color/white"
                    android:textSize="12sp"
                    android:textStyle="bold" />
            </FrameLayout>

和我的代码中的uisng渐变为：

int sdk = android.os.build.VERSION.SDK_INT;
        if (sdk < android.os.build.VERSION_CODEs.jeLLY_BEAN) {
            placeHolderImageViewAbout.setBACkgroundColor(getresources().getColor(R.color.transparent));
        } else {
//shadow BACkground is above mention gradient
            placeHolderImageViewAbout.setBACkgroundresource(R.drawable.shadow_BACkground);
}

<item>
    <shape android:shape="rectangle" >
    </shape>
</item>

FrameLayout
(BACkground = @color/light_green)
    LinearLayout
    (BACkground = @drawable/shadow_BACkground)