I'm trying to run a stress analysis on a steel weldment (built as an assembly out of some extrusions) and I get the simulation set up to run, but when I run it I get the error message: "Please define Elastic modulus in material properties"  I have assigned all of the steel with the "plain carbon steel" material that is set within the simulation software and it ran earlier but just seems to have decided to stop working.  I don't know if I did anything to cause this or if it is some interesting "feature" within the software but I'm definitely getting frustrated with it.  I looked at the material and the elastic modulus is defined.  Any suggestions or help would be appreciated.