How can I use a used SAVE file for Naruto Shippuden Ultimate Ninja Storm 2 on the PS3?

I'm trying to play my game, but I don't want to go through all of the pointless side quests and go straight playing story missions. I was intending on doing this by going on gamefaqs.com and using another person's completed save file and just replay the mission from there. However, when I tried doing this, I got a message saying that the save file doesn't match up, and it wants me to delete it. I did the exact same process as I did for the preceding game, and it worked. Is there any way I can bypass this?