Joints don't stay in place during walk cycle_ Character Animator

I have made this sample character in photoshop and tried wal cycle in Character Animator using rigging method taught by OkaySamurai on Youtube. Sometimes my rig works just fine but sometimes it behaves weird. I am trying hard to get the joints stay in place during walkcycle but they move as soon as character starts walking, which looks odd. What mistakes am I making in rigging? Attached is the puppet.