not sure, if anyone is still reading this but it has been covered in another threat but i'll give you a possible solution. If when you load the game you're getting the black screen complaining about no save and to reset the DS try this.
1. Load game and wait for error.
2. Take MicroSD card out of DSTT and put in reader, place in pc and browse to the folder where your games are.
3. Look for a file that says CONTRA 4.SAV(this is the problem file).
4. Rename the file to Contra 4.sav and it should work.
I ran into this problem myself and that is how I remedied the situation and the game runs fine now.