I have a structural assembly of a large trailer that I want to simulate the stress and strain. I am new to the simulation software and am starting small.  I have 6 subassemblies that I put together and was able to successfully mesh and run all of them seperately. (Static test) 

When I put them together and try to run the assembly, I get an error: "May have bad(distorted) elements. No result saved."   What does this mean and how can I fix it?

Another error I have gotten is "Element voume is smaller than limit.."

Any help is appreciated I just started using the software last week. Thanks