Story stacking - automatic elevation setting

[Tom B]

I'm a VWcad 10 user new to 2012 and I'm having trouble with setting up a set of stories and associated design layers for a simple 2-story building with basement and roof. Specifically, I have successfully set up the basement, 1st & 2nd stories, with associated design layers at the correct elevations. But when I try to set up a third "roof" story, it wants to set an elevation 13-1/2" above the highest design layer element, which is the ceiling, in the 2nd Floor story below. If I set my new "roof" story at the desired correct elevation and add a "roof" design layer in that story, I get an error message saying that this overlaps with a plane from the story below and won't let me do it. i have looked at every design layer in every story and can't seem to find anything that is higher than the elevation of the ceiling design layer in the story below. I have also looked at all of the default design layer choices and set all of the offsets and default heights to zero, just in case this might be the problem. The 2nd story elevation is identical to the 1st story ceiling elevation and that relationship works fine. same with the basement. But not with the 3rd "roof" story.

My "Stories," with associated design layer elevations:

Story 3 (roof) should be @ 18'11-3/4" (but defaults to 20'1-1/4", 13-1/2" higher than i want)

Story 2 (2nd Floor - 8' ceiling) @ 10'0-5/8" with design layers:

Ceiling 2 @ 18'11-3/4" (8'11-1/8" offset from story for 8'1-1/8" wall ht)

Floor 2 @ 10'10-5/8" (10" offset from story for 10" floor deck with 8'1-1/8" wall ht)

Slab 2 @ 10'10-5/8" (10" offset from story for 10" floor deck with 8'1-1/8" wall ht)

Story 1 (1st Floor - 9' ceiling) @ 0'-0" with design layers:

Ceiling 1 @ 10'0-5/8" (9'11-1/8" offset from story for 9'1-1/8" wall ht plus 11-1/2" floor deck & plate)

Floor 1 @ 0'11-1/2" (11-1/2" offset from story for 10" floor deck and 1-1/2" sill plate with 9'1-1/8" wall ht)

Slab 1 @ @ 0'11-1/2" (11-1/2" offset from story for 10" floor deck and 1-1/2" sill plate with 9'1-1/8" wall ht)

Sill Plate @ 0'-0"

Story B (Basement) @ -9'0" with design layers:

Ceiling B @ 0'1-1/2" (1-1/2" offset for sill plate)

Floor B @ -8'0" (12" offset from story for 8" footing and 4" concrete slab, with 8'1-1/2" wall ht)

Slab B @ -8'0" (12" offset from story for 8" footing and 4" concrete slab, with 8'1-1/2" wall ht)

Footing B @ -9'0" (0'-0" offset from story)

Any thoughts on why the 3rd "roof" story won't default to the highest "Ceiling 2" elevation and wants to add another 13-1/2"? I can't find any combination of design layer elements that results in that dimension difference.

Ironically, i can create a "roof" design layer without creating a "story" for it at the correct desired elevation, but when I try to assign it a "story" at that same elevation I get the same invalid error message, saying there is an overlap.

Here is a link to screen shots of my stories and design layers dialogue boxes, if anyone is interested.

http://tb-images.weebly.com/image-gallery.html

TB