MBA not waking up when tapping on trackpad even if 'tap to click with one finger' enabled.

I have enabled 'tap to click with one finger' on my MBA 11' (early 2014) but that won't let me wake up the laptop when I put it to sleep on battery. It only wakes up if I clicked any keyboard key. But, different case happens when MBA is plugged in; tapping on the trackpad easily wakes it up.