Ds game won't play on my Nintendo 3ds xl!?

I was told that the new 3ds xl would be compatible with ds games.

I have tried plugging in Pokemon diamond and Black version 2 but every  time it goes to a black screen with the message "An error has occurred.  Press and hold the POWER Button to turn the system off. Please refer to  the Operations Manual for details."

How can I fix this problem?