My dog BUtters couldn't learn sit for like more than 6 months lol! Now she knows it really well, and even knows how to go to bed!! Sometimes the learning curve is a bit slow, but just keep educating yourself on how to properly train a dog, and make sure your training is very short, and frequent throughout the day. At this age, you really just need to focus on bite inhibition, socialization, learning how to sit, come, and stay. I would just focus on those basic ones before moving into tricks and other obedience commands.