I don't like when people give non answers like this, but your best bet is to use a third party software.
The built in Windows Backup and Restore has always been wonky in some fashion. My personal favorite is creating a sys image, right after a clean install of Windows 7, when it errors on right at the beginning saying there's not enough room on the drive to create a VSS copy, because the system partition is only 37MB or something like that, and it needs at least 40 MB. And recovering from an image can be a pain. The image must be in the 'WindowsImageBackup' folder and if there's multiple images in that folder, Windows can get confused. I also love how it won't let you back up to a flash drive, but you can make the flash drive a shared drive, map it as a network drive and trick windows into backing it up that way.
Acronis True Image can be had for about $30 or cheaper if you get a version from a couple years ago. Creating system images and setting up full and incremental back up schedules are dirt simple. You can make an Acronis boot CD or USB flash drive that you can boot off of to recover data and clone drives. If you need to recover a specific file or a set of specific files you can browse the contents of the TIB file in the a File Explorer window and copy and past specific files back to their original location.
If data backup, data retention and creating system images are important to you, I would not rely on Microsoft's own backup utility, since as you can see, it is not that robust. If you don't care about system images and setting up a back up schedule, and just want a daily or weekly copy of your My Documents or My Pictures folder, I would probably just schedule a batch file to run every week or whatever that copies the contents of specifically defined folders to an external drive or a NAS.