Referring to other posts, it seems that it is good practice to refer to the parent component literally as (Parent!wantedAttribute) So for shelf#1," =(Parent!Lenx)" instead of "=cub#1!LenX" or for the other "=cub#2!LenX"; works for both without problems, a much better way to go..for reuse.
"Re: copies of DC cabinet door not working properly"
Jim says.....
I also prefer to use the 'Parent' word to reference the parent component. This makes sub-components more interchangeable with other DC's, so you can change-out sub-components more easily.
we live, we learn.....