Android - RelativeLayout inflated as Button?

Question

I have a weird problem. While running my Android application, I receive Exception:

java.lang.ClassCastException: android.widget.Button cannot be cast to android.widget.RelativeLayout

the code, where I try to get relativeLayout

v = inflater.inflate(R.layout.home, null);
RelativeLayout btn = (RelativeLayout) v.findViewById(R.id.my_button);

in xml, I've got this:

<RelativeLayout                
                android:id="@+id/my_button" 
                android:layout_width="fill_parent"
                android:layout_height="fill_parent"
                android:background="@drawable/button_selector"/>

While debugging, I've noticed that in v there is Button with mID equals to R.id.my_button.

Although, when I change id in xml and code to anything else, I receive NullPointerException.

Any ideas why this is happen ?

EDIT: Maybe it will be helpful, if I add that in older version of that file there was Button, but was replaced with RelativeLayout. I'm using GIT. Project was cleaned many times and eclipse was restarted also.