I cannot figure out mistake here. I may be oevrlooking some thing...
Layout XML:
try this:
View v = getlayoutInflater().inflate(((LinearLayout)findViewById(R.id.headerInclude)), null);
TextView tvTitle = (TextView) v.findViewById(R.id.tvScreenTitle);
If you set the id attribute for the include element, then that will be the id for the root of the inflated layout. So, instead of looking for a LinearLayout with the id headerLayout look for the id headerInclude(or don't set an id for the include element).