Adding web tile layers to non web mercator webmaps

Discussion created by dstubbins on May 14, 2013
I have a basemap that is tiled but not in web mercator.  I also have a tile layer that matches this (non web mercator) basemap tiling scheme that I'd like to overlay.  When I add it, it says it does not match the tiling scheme of the underlying data.
I can add the tile layer on top of a web mercator base map.
obviously Arcgis.com has no way to know whether it matches or not  (apart from tile size).  Is it a bug that it wont add it to my basemap? or by design?