How Do I Take Screenshots On A Smasung Galaxy A3?

i've been trying to Take Screenshots on my Samsung Galaxy A3 by using both the "Home+Lock" Key Combination and "Volume Down + Lock" Key Combination and neither have worked... and no , i don't want to Install a Screenshot App on my Device...

does anyone know how to Take ScreenShots on it? (without Downloading Screen Capture/Screen Grab/Screen Shot App)