"Let's model me a mine"
M.E.G.M.S.
Mining & Exploration Geological Modelling Services
An entry in the configuration file referred to an element that had not been defined. Examples might be a hatch list refers to a vector definition that doesn't exist.
Check that the name is spelt correctly, and exists in the appropriate section. Check also that the sections in the configuration file appear in the right order, so named entities are defined before they are used.