When using an ImageButton with this XML:

and the following drawable XML:

```
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@drawable/bruin_s1" android:state_pressed="false" /> 
    <item android:drawable="@drawable/bruin_s2" android:state_pressed="true" /> 
    <item android:drawable="@drawable/bruin_s1" android:state_focused="false" /> 
    <item android:drawable="@drawable/bruin_s2" android:state_focused="true" />
</selector>

```

It will crash when I click that button with this exception:

```
06-17 10:18:23.028: ERROR/AndroidRuntime(290): Uncaught handler: thread main exiting due to uncaught exception
06-17 10:18:23.048: ERROR/AndroidRuntime(290): java.lang.IllegalStateException: Could not execute method of the activity
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at android.view.View$1.onClick(View.java:2031)
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at android.view.View.performClick(View.java:2364)
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at android.view.View.onTouchEvent(View.java:4179)
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at android.view.View.dispatchTouchEvent(View.java:3709)
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884)
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884)
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884)
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884)
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1659)
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1107)
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at android.app.Activity.dispatchTouchEvent(Activity.java:2061)
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1643)
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at android.view.ViewRoot.handleMessage(ViewRoot.java:1691)
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at android.os.Handler.dispatchMessage(Handler.java:99)
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at android.os.Looper.loop(Looper.java:123)
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at android.app.ActivityThread.main(ActivityThread.java:4363)
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at java.lang.reflect.Method.invokeNative(Native Method)
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at java.lang.reflect.Method.invoke(Method.java:521)
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at dalvik.system.NativeStart.main(Native Method)
06-17 10:18:23.048: ERROR/AndroidRuntime(290): Caused by: java.lang.reflect.InvocationTargetException
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at nl.ivaldi.borre.Drawing.onColorClick(Drawing.java:135)
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at java.lang.reflect.Method.invokeNative(Native Method)
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at java.lang.reflect.Method.invoke(Method.java:521)
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     at android.view.View$1.onClick(View.java:2026)
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     ... 20 more
06-17 10:18:23.048: ERROR/AndroidRuntime(290): Caused by: java.lang.ClassCastException: android.graphics.drawable.StateListDrawable
06-17 10:18:23.048: ERROR/AndroidRuntime(290):     ... 24 more

```

However, when I change the drawable to one of the images (i.e. bruin\_s1) it will work just fine. What's wrong?