I can't really take credit for Dagfinn's work on the model you uploaded (thank you Dagfinn), but I am glad it is working and was happy I could help earlier on.
The error could have crept in if you adapted a model that has been scaled a few times, or something like that. If it is something simple enough, then it can be quicker just to do things from scratch, rather than hunting for ages to find the problem, although this time it might be useful to try and work it out.
For learning about DC's I would recommend looking at google's examples of how to use various functions (they have some collections on the 3DWH) and just playing around to see how things work and what you can get them to do. That is how I learn things anyway, it might not suit everyone.