Backup and restore

I have a course running on Moodle 1.9 Beta + (2007091900) where I backed up a course. Then I did a clean installation of Moodle 1.9 Beta + (2007092001) and I tried to restore my course into a new course. But I got this error, shown in red below:

• Creating new course
  • Curso de Introducción (CI101)
  • Category: Miscellaneous
• Creating the Restorelog.html in the course backup folder
• Creating users
  . . (New: 15, Existing: 0)
  • Students: 0
  • Teachers: 0
• Creating groups
• Creating groupings
• Adding groups into groupings
• Creating sections
• Creating categories and questions
• Copying user files
  • User zones: 1
• Copying course files.
  • Files/folders: 2
• Copying site files used in course
• Creating scales
• Creating events
• Creating course modules
  • Forum "News forum"
  • Forum "Usando un foro de Moodle"
  Could not restore modules!
• Creating roles definitions
• Creating course level role assignments and overrides
• Creating module level role assignments and overrides
• Creating block level role assignments and overrides
• Creating user level role assignments and overrides.
• Closing the Restorelog.html file.