Geoprocessing+flex

I have a model in ArcGIS 10.1 that user should draw a line on the map and model convert it to a 3d line.When I run model by ArcMap every thing is ok, but when I run model by flex viewer, it return this error in the message of arcgisjob:
geometry can not have z values.
what is wrong on my flex viewer 3 or geoprocessing?
Regards
A.ponker