WMTS Error

Hi All

I have added a OGC WMTS service to my GXE 4.2.1 site and I am getting the following error

The following warnings were encountered:

The RequestEncoding property on map service "SA Internal Imagery and ArcGIS Online mosaic" (ID: "3") is invalid. The value "RESTful" is not supported.

The Silverlight viewer (2.3.0) seems to be operating OK, that is the imagery is displaying OK however the when I try and export the map or print the imagery is returned as blank.

Any suggestions?

Cheers

Chris