unit´s power

I attacked with my 4 units area with 1 unit and I lost. than I attacked with my 7 units area with 4 units and I lost. why? is this normal?
Conquer Club, a free online multiplayer variation of a popular world domination board game.
https://www.conquerclub.com/forum/
https://www.conquerclub.com/forum/viewtopic.php?f=6&t=108011