Void Sweep Angle too small???
I think that the object turns on itself. Basically you ask that Revit removes (or adds) pieces were already things have been removed. Revit does not know how to handle this. What you might try to do is to do it ins two steps (two void sweeps)
Louis
Please mention Revit version, especially when uploading Revit files.
The only other way around is to try to make it additive. What you are doing now is taking away stuff. Try it the other way around. Build up your parts by adding stuff to it.
Revit tools are not made for the finer modelling. It just does not have the algorithms to solve what you are asking it. Revit is always meant for the simplified versions of real life objects. This to keep projects manageable.
You will see that software like inventor have much more tools an functions to deal with these kind of things. However these software are more geared to smaller things (e.g single machine), not complete buildings.
Louis
Please mention Revit version, especially when uploading Revit files.
See the video in the URL below
This should give a better idea of what I'm trying to do, maybe I'm not explaining it very well. The first unit shows what I'm trying to do, within a rectangular shaped PC unit, and Revit has no problem doing this. The second unit is what I need to do, where depth and width of the unit are the same, but on one side, instead of being 90 degrees edge it comes in on itself by 19 degrees, and then won't cast the unit. I need this to stay within the confines of the shape (no protrusions) hence why I can't add a piece that shape ontop as it protrudes from one or more sides? Am I making any sense to anyone?? 
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