From this small little errormessage I think your HttpContext might be null.
But it is impossible to say more without seeing the whole stacktrace and the code where it happens.
Thank you guys,
It was a problem with a IIS. After fix the .net 2 with IIS 7.
Good that it worked out. IIS and framework proplems can be hard to solve sometimes.
I have this error. I don't know much abou the project.