The gap tooth rat

This piano app is really really good and it helps me a lot with my piano and no ad's 😆but there are a few problems, like songs when you first log into the app you can chose one song but if you want to try another my phone will say " sorry there was an error with the purchase" and then I can't any song at all And when you don't have a piano and your using the app to play it sometimes the note won't play. But yeah this is all the thing that are bothering me with this app but can you please fix these errors