Hi Mihai Persa all american ds games do not work on the DSi but if you have the original DS or DS lite they will work fine. For some strange reason Nintendo did'nt make the DSi region free which sucks a little. Also they took away the GBA game card slot which could also be used for the guitar hero add-on too. On a more positive note the DSi has DSiWare which good for buying cheap fun games and full internet. So pros and cons my friends anyway I hope you all have a fantastic Christmas.
The only games that are not region free are games that use the DSi's features such as the camera. This game however is region free as it is not a DSi game. As such if it doesn't work on a DSi then it means you got a bootleg copy.