getHeaderHeight always return '0'

[yooncheolkim]

• Java code:
  Log.d(LOGTAG,"header view height = " +gridView.getHeaderHeight(0));

• log :
  05-15 14:49:14.164 8976-8976/com.example.yoonc.dmyphoto D/MAINACTIVITY: header view height = 0

As you see this result , gridview has a yellow headerText. But getHeaderHeight always return 0...
Please help me...