The Dina robot could've been walking in a stiff and rigid manner due to an inadequate code controlling the degrees of freedom at joints, and ineffective balance and gait consolidation algorithms are the usual causes. Sometimes feedback and communication channels between parts could cause a slow reaction in motion sensors and actuators, such that it would seem that the robot is hesitant or unsure in gait.
In general, it's difficult for a humanoid robot to walk like a human being. Humans joints-even relatively simple ones like knees, have much more flexibility. Everything other than finger and toe joints has some side to side play. Simply put, motors and gears don't work like muscles and tendons.