[MapProxy] ESRI basemap

[paula.almeida at ipma.pt]

Hi,

I'm trying to create a cache basemap of esri with the following 
configuration:

services:
   demo:
   kml:
   tms:
     # needs no arguments
   wms:
     srs: ['EPSG:900913']
     image_formats: ['image/jpeg', 'image/png']
     md:
       # metadata used in capabilities documents
       title: MapProxy WMS Proxy

layers:
   - name: agslayer
     title: ArcGIS Online
     sources: [ags_cache]

caches:
   ags_cache:
     grids: [GLOBAL_MERCATOR]
     sources: [ags_rest]

sources:
   ags_rest:
     type: tile
     url: 
http://server.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer/tile/%{z}/%{y}/%{x}

grids:
   arcgis_online:
     tile_size: [256, 256]
     srs: EPSG:900913
     origin: nw
     num_levels: 18




the tiles are shown incorrectly, appear split on the image

Any ideias?

Regards,
Paula