How to make a sketch line twice as long as another?

Would like the dark blue line to be twice as long (and midpoints aligned) as the light blue line. I tried the following:

  • Smart Dimension > "2*" + click the blue line

Expected:

A relationship to be formed between the two sketch entities, and the green OK to work.

Actual:

I get this funny black/red equation with a lone quote mark at the end. OK tick does not work, nor give an error.

I then tried:

  • removing the lone quote
  • adding a quote just after "2*"
  • renaming the sketch so there's no space in its name

None of these mattered.

Is this a bug?

How would you form such an innocent-looking relation between two sketch entities?  (Limitation: I don't want to add a global variable for this.)

Solidworks 2019 Beta 2

SolidworksSketching