Community
You can try to delete the license file and re-start your program, get the requirement code to apply your activation code.
The license file location is :
For Windows XP OS: C:\Documents and Settings\All Users\Application Data\Autodesk\Software Licenses (with extension .dat)
Windows Vista and 7: C:\ProgramData\FLEXnet (with extension .data)
Emily Xu, Autodesk Product Support
We appreciate your quick feedback on this forum