Not a valid date in accord with the XML format for ABAP

All,

I have read seemingly every article about dates and GW services but still cannot solve this one.

I am attempting a POST with a deep insert (I don't think that is related but maybe), the payload is JSON and I am formatting the date like this:

"MyDate":"2015-02-08T00:00:00Z",

In SEGW the date is formatted as Edm.DateTimeOffset and typed as DATS with 0's for the Precision, Scale and Max Length and Nullable is checked.

The response I get back is:

Value 20150208000000 is not a valid date in accord with the XML format for ABAP

I have tried clearing the cache with:

/IWFND/CACHE_CLEANUP and

/IWBEP/CACHE_CLEANUP

Any ideas?

Thanks, Mike