I'm using ArcGIS 10.3
I have two shapefile, one customer and one of Facilities
each shapefile has the field "distributor"
I'm using the tool "Location-allocation_ Network analysis"
I need to keep the groups already established in my Shapefile "Customers" to the field of "distributor
I used the option "GroupName" but it's not possible I have Failed error Solve
Error No feasible solution can be found due to name constraint group
as I can fix the error
The GroupName field is used for Demand Points to make sure that the points with same name will be served by the same facility. But you cannot specify the exact facility that will be chosen to server them. The solve will figure out the best facility. You can however make your existing facility "required". That way the required facilities have to be in the solution and this MAY give you the correct answer if your existing facilities are near the optimal locations (as the demand groupname will force the entire group to be served by one facility).