When I go to the store and click "New tack" It won't let me buy anything. I click the buy button but I don't get it in my inventory. I can still buy the used tack though.

Maybe you don't have enough ebs to afford new tack. Check that, otherwise, I'm not sure.

You also can't just click buy. You need to enter a quantity

Thanks! It works now, I did not remember that I had to put a number XD