code: public void setActionLabel(CharSequence label){
          mEmptyActionText = label;
          mAction.setText(mEmptyActionText);
          mAction.setVisibility(TextUtils.isEmpty(mEmptyActionText) ? View.GONE : View.VISIBLE);
      }
docs: Set the action button label, this in-turn enables it. Pass null to disable.
  
  @param label     set the action label, thus enabling it