symbolic evaluation not evaluating symbolically

I am working through this tutorial (from this site), using Mathcad Prime 3.0, F000  The thing that is driving me absolutely crazy is tha tI can't get it to solve symbolically, like the tutorial says it should. 

I am trying to do this problem:

However, when I insert the symbolic operator, this is what happens:

Why am I getting a numeric solution instead of a symbolic one?  It's especially frustrating since one would thing a PTC-supplied worksheet would, you know, work.

Any input is appreciated.

Thanks.