You have 2 types of buttons; one is a single pole and the other one called a single throw. To explain this as simple as I can, the difference is single pole usually used with a standard doors bells, you press and it has a standard bell ring and to make it ring again you have to press it again because as soon as you release the button the power flow to the bell stops.

When you have a single throw which is used with most chimes that play music, or other fancy sounds, they need to have a continued flow of power going to the bell after the button is released so the music or whatever sound is programmed can finish its cycle.

So most likely you have a button that serves as a single-pole door bell and you need Diode.

I hope it explains or take a look at This Video

Good luck