Problem: Visible scale dependent sub-layers do not get drawn properly at minimum/maximum scale values
ArcIMS image service sub-layers can be set to draw within a certain scale range. In ArcMap, if you set the map scale to the minimum scale value of a particular sub-layer, the sub-layer will not draw.
ArcIMS 3.0 calculates extents differently than ArcGIS does.
Solution or Workaround
Upgrade to ArcIMS 3.1.