Revit Error: "Extension Layers at the base of the wall must be adjacent"

Came across this error that really perplexed me... it was the verbiage that Revit used that I didn't understand...

 
After hunting through the actual wall assembly I found what the problem was and the message then made sense.

what I found that if you have more than one wall layer component at the base (or top) that is unlocked to make it extendable they need to be next to each other. You cannot have one layer unlocked and it's adjacent layer locked.

This only applies when you have multiple layers that are unlocked. you can have a single layer unlocked anywhere along the assembly but as soon as you unlock another layer they need to be next to each other.

Here are some examples:

Any one Wall Component Layer Unlocked is OK.

Any two or more Wall Component Layers Unlocked that are next to each other (or adjacent) is also OK.

Revit will not allow two or more Wall component Layers that are unlocked that NOT next to each other. Hence the error message that you cannot ignore.