Unlock patterns using adb sendevent in Android

After checking some answers:

Is there a way to unlock android phone via adb, if I KNOW the pattern and Unlock Screen Galaxy Nexus ADB

Im trying to unlock a pattern using adb commands using this script http://ift.tt/1QZWYIx (for automation purpose).

Unfortunately the events arent working but I noticed that if I turn on the screen by myself (without using adb shell input keyevent 26) while the script is running, the events work and the pattern unlock.

Could someone explain me why this is happening and if there is another way to unlock patterns? maybe without using events (like I wrote before is for automation purpose, not for a phone that was locked).