The value of the scalebar acetate layer is zero for an ArcMap Service
There two known issues that may cause this:
1. **This issue has been resolved in ArcIMS version 4.0.1**
The scalebar value will be zero when the original map is in projected coordinates and the FILTERCOORDSYS in the GET_IMAGE request is in Geographic coordinates.
** This issue has been resolved in ArcGIS 9.0. **
The spatial extent of the map is such that the scalebar is a fraction of the map's unit of measure. For example, if the map's unit of measure is in kilometers and the spatial extent of the map is less than a mile, the scalebar value is zero instead of a fraction of a kilometer.
If you are using ArcIMS 4.0, use the same projection to specify FILTERCOORDSYS in the GET_IMAGE request as in the Service.
Scalebars for ArcMap Services (versions 4.0 and 4.0.1) do not support fractional units. To have a usable scalebar use smaller units. For example, use meters instead of kilometers.