New shop bug

I cannot add new item in the shop section, after pressing the 'Create new item' button, i have an error :

Server Error in '/' Application.
--------------------------------------------------------------------------------

Unable to validate data.
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: Unable to validate data.

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.

Oh, that's why no one's been posting anything lately. Thanks for letting me know. It should be fixed.

My bad. I didn't name the live version of the file correctly. That sure is a scary sounding error though, eh?