Invalid format for date in Odata

Hi

I have a date issue in my odata.

The error is:

Invalid format (return table): Row Number 1,  Property Name 'ZzKstromDato',  Property Value ''

It seems that even that my properties is set as nullable, I still got the error.

I have found this link, but that doesn't do the trick for me :-(

500 Internal Server Error while executing Gateway Service

Anyone who will help me?

thanks

Lars