ok i managed to do the enableviewstate thingy :-) but i still get
The viewstate  is invalid for this page and might be corrupted.
Description: An unhandled exception occurred during the execution of the current
web request. Please review the stack trace for more information about the error
and where it originated in the code.

Exception Details: System.Web.HttpException: The viewstate is invalid for this
page and might be corrupted.

Source Error:

An unhandled exception was generated during the execution of the current
web request. Information regarding the origin and location of the exception can
be identified using the exception stack trace below.

Stack Trace:

[HttpException (0x80004005): The viewstate is invalid for this page and might be
corrupted.]
System.Web.UI.Page.LoadPageStateFromPersistenceMedium() +150
System.Web.UI.Page.LoadPageViewState() +18
System.Web.UI.Page.ProcessRequestMain() +423