the latest dsi firmware (dsi v1.4.2) blocks the use of unofficial software - in this case, your r4i gold. But r4i gold has the capability to update it's bootstrap in order to make the DSi think it's a legit game.
I'm not sure which r4i gold cart you have, as there are multiple r4i gold carts. Maybe you could give us the website written on the sticker of your cart or on the box?