Inflating custom view causes error-Collection of common programming errors

I have created a custom view that includes an ImageButton and a TextView. This is my layout:

I also have a class that inherits from RelativeLayout called CustomImageButton. This is part of it’s code:

public class CustomImageButton extends RelativeLayout {

    ...

    public CustomImageButton(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.attributes = context.obtainStyledAttributes(attrs, R.styleable.CustomImageButton);
    }

    @Override
    protected void onFinishInflate() {
        super.onFinishInflate();

        ((Activity)getContext()).getLayoutInflater().inflate(R.layout.custom_image_button, this);
        this.setClickable(false);
        setupViewItems();
    }

    private void setupViewItems() {
          // DO STUFF HERE TO THE IMAGE BUTTON AND TEXT VIEW
          // FROM THE CUSTOM ATTRIBUTES 
    }
}

These are the custom attribute given to the Custom image button: (attrs.xml)

and finally this is the main layout:

and now, for the problem. When i run my application on android 4.0.2 and higher everything is ok BUT, when i run my app on android 2.2.1 i get

android.view.InflateException: Binary XML file line #5: Error inflating class 

according to the stack trace (which is VERY uninformative) the exception is thrown from the CustomImageButton class in the onFinishInflate method when i call the inflate method. Any ideas why and how can i fix this?