Project transformation from WGS84 to 31370 (Belgium Lambert 72)

Discussion created by johnny.penet-esribelux-com-esridist on Jul 15, 2012
Latest reply on Aug 16, 2012 by johnny.penet-esribelux-com-esridist
I am trying to add Google Places at a map with a basemap having spatial reference 31370. Because Google gives the result in WGS 84 coordinates, a project transformation is needed to convert the result into spatial reference 31370. For the project transformation I use the project method of the geometry service of an ArcGis 10.1 server (REST service).
The results have a displacement of some 100m in x and y, probably due to the fact that no datum correction has been done in the project method.
In the list of possible transformation for 31370, i found several possibilities :


It is not clear what the differences are, but all give me the same results.

I also use the same method for doing the reverse transformation, from spatial reference 31370 to WGS84. This works fine, and give me the correct coordinates.

Conclusing, in one direction it works, the other way not. I also used different transformationForward parameter options, but same errors.

When I use a basemap with spatial reference 102100, no problems (but I don't need using the geometry service).

Is this a limitation of the geometry service project method, handling the transformation in one direction in case of the spatial reference 31370?