StartDate is invalid or in the wrong format. For detailed help with formatting, see http://sellercentral.amazon.co.uk/gp/help/24921
This error occurs when the start date for your sale is improperly formatted or invalid. For the start date to be valid, it must be:
To resolve this error, please resubmit your data using a sale start date that is properly formatted and prior to the end date for your sale.
If you are using inventory files to manage your products and sales, Microsoft Excel may have reformatted your start date when you entered it in your inventory file template. To prevent Microsoft Excel from reformatting your date: