Hi Everybody, thanks for the replies once again!
I tried what Alvin suggested but with no luck, I also tried what Henry suggested with repairing the installation again with no luck.
After some long hours last night my thinking was that it may be "me" not understanding the program correctly & the limitations rather than expectations of what can & can't be done in the program.
I am confident I have found the cause of my concerns & I am not sure if the program should not do what the problem is.
Maybe I have no idea either being a CAD novice!
I have attached a very simple file of a box with two "polylines & the simple extrusions from them".
You will see the simple extrusions assembled to the main box in the center, the rectangle extrusion has been reduced in the Z Axis to be within the constraints of the main box & this will 3D Add without problems.
If you now increase the Z Axis beyond the Top of the center box the program will not 3d Add the components together. The same applies on any Axis.
The Triangle extrusion is overlapping the center box & will not 3d Add to the center box but if you assemble the small end of the triangle to the center box or reduce the size of the triangle to be within the constraints of the center box it will 3d Add without problems.
It seems that if there is an overlap things will not 3d Add together?
With my three piece component "ABOVE" the two outside pieces created overlaps & hence the issues with the 3d Add.
Is this normal?
If it is, it would be nice to have no constraints due to overlapping pieces!
One would think that having overlapped components shouldn't be an issue, it is 2016 after all
Am I on the right track with this?