Don't want to start the game :S

When i copy nds file from anygame i download, and start it it trows out me a message "File is corrupted", or "Couldn't load the game", or "Couldn't make save file". It happens me all the time on every game i want to start!
Pls help me guys! My DS card i use is M3DS Simply.

Backup all your files and reformat your MicroSD. Make sure you have the latest firmware. http://linfoxdomain.com/ds/