Hello and welcome to Pets.ca!!
I have a couple of general questions for you....
1) What kind of dog is Luna
2) What type of collar are you using
Does she know the commands such as :
Look at me or something that her focus is you and only you
Does she have a favorite treat above anything else that she would go for...
Sorry my question mark isnt working on my keyboard...LOL
It sounds like to me that she is not taking you serious enough or she is not in to you so to speak...a lot of training will place the focus on you as the dominant one that she would look up to...
If she knows look at me or a command that focus on you I would start there. I would put her in a situation where there is another dog around to test her. If she doesnt focus on what your asking her to do I would give her a slight pop correction on her leash and say look at me...you can raise your finger up to your nose and point and say ahhh (almost like a growl) look at me...it is sometimes hard to explain but you need to distract her attention from the other dog and reward her when her focus is on you...if you have a friend with a dog it might work better to practice with them...
Never ever continue to walk when she is doing this because it is almost like rewarding her. You may have to plant your feet on the ground and stand there for 10 minutes until she settles and then move forward....
You never want to reward the dog for doing what it shouldnt be doing...only reward when they listen or do what you want...
Hopefully this makes sense...
Looking forward to hearing from you more.....please dont give up...you can teach them......
P.S My previous dog..RIP was always the example in obedience class and now I have another nut bar that took a lot of training....LOL
Cindy