"Can't create" error message for beams

[Anonymous]

I'm trying to make a hip and valley beams for my roof.

I'm using "Structure > Beam > pick line" method. 

I have "3d Snapping" checked off. 

But I get an error message saying "can't create."

Does anyone know how I can fix this?

[Anonymous · Accepted solution]

I found the solution to my own problem. 

Just putting the answer out there so that someone struggling with the same error message find a solution.

Step #1: 

Structure> Work Plane> Set (Work Plane) > Specific a new Work Plane > Select "Name" > then choose a level (I chose 'Top of Plate' level for my model)

Step #2: 

Structure > Beam> Make sure '3d snapping' is checked off

It should work after doing the steps above.