Norton 360 Backup failed error unknown

Hi, everytime i try to back up my entire c drive it always fail. it just says error, when i click on more details it doesnt show any error message at all or any recommended steps. I searched the forums, and what i found is I should try to create another backup set and delete my old one tried this and it failed. it gets all the to 99% during the backup and when it completes it just says error but when I go to check my usb drive the ammount of data the backup says it will take like 4gb is always there. I hope this post makes sense i need help on how fix this. From what it looks like on my usb drive the backup completed because of the size of the backup, but norton360 says error. I have the log sheet from it been trying to figure out how to post it on here.