I'm experiencing some difficulties trying to create a simple window with two sliding panels. I need to create one parameter to set the window height from the reference level (2,1m), and another for contro11ing the window's sill (with a range between 0,9m to 1,1m). Very simple, but in Revit it brings some further complication.

The standard Height parameter only moves the upper reference plane, leaving a 0,80m sill. An aligned dimension linking the upper plane to the reference level with a custom parameter (Janela_Altura = 2,1m) doesn't work as Revit pop-ups a message: Labeling this dimension would overconstrain the sketch. I don't understand why such a simple model can't have this labelled dimension!


Any advice will be very useful.
Thanks in advance