Abnormal behavior with RadioButton

I am using RadioButton

in my layout. Where I presented the background RadioButton

. Below is the code

<RadioGroup
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="horizontal">

    <RadioButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:button="@null"
        android:background="@drawable/rb_spain"
        android:id="@+id/am_rb_spain" />

    <RadioButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:button="@null"
        android:background="@drawable/rb_germany"
        android:layout_marginLeft="@dimen/margin_15"
        android:layout_marginRight="@dimen/margin_15"
        android:id="@+id/am_rb_german" />

    <RadioButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:button="@null"
        android:background="@drawable/rb_english"
        android:id="@+id/am_rb_english" />

</RadioGroup>

      

        
        
        
      

    

RadioButton

background extraction

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android" >
    <item android:state_checked="false" android:drawable="@drawable/ic_spain" />
    <item android:state_checked="true" android:drawable="@drawable/ic_spain_pressed" /> //pressed image is Large in size
    <item android:drawable="@drawable/ic_spain" /> <!-- default -->
</selector>

      

        
        
        
      

    

I saved the selection in TinyDB

so that the application remembers my selection when I open my application. But whenever I open my application, the default selected background of the RadioButton appears Large. I took all images of the same size, drawable with the same padding.

The first flag is the default selected here. But it looks a little big in size

Now I have pressed the second flag. But the first flag does not come up to normal.