Error Creating Quote Header through REST Services

Trying to use REST Services to create Quote Header gives application error “cannot convert string into date/time field” We are using the customercustid and shortorder date for the due date or we try it without the due date and it gets the same error. Should be a pretty simple creation of the Quote Header but we keep getting the same error and the app serve

We are synching SalesForce with Epicor using a Jitterbit built application

Anyone else trying or doing anything like this? The App Server errors are not very helpful except for the same string conversion error