This Value Must Be A Scalar or a Matrix - Prime 8

Hello,

Sorry to post on a subject that others have before, but I am getting wrapped around an axle and could not understand the prior posts.  How do I turn my alpha variable into a scalar or matrix?  I've tried to highlight the number and units then select 'matrix', but that did not work.

I would greatly appreciate some direction.  My Prime 8 file is attached and a screenshot is below:

V/r,

Devin