I'm working with ArcGIS server 10. I developed a model builder that contains "point distance" task which requires feature layers as inputs. The model was added to a map (.mxd) that uses two feature classes. I tried to execute the services using ArcGIS Services Directory: as inputs, I put the paths of my two feature classes (as I did with one of them with the "buffer" model which works). However, the server shows an error and asks to check your parameters. In Arcgis resource help (Key concepts for geoprocessing services) it says that "Feature Class input is supported indirectly with the Feature Set data type".