missing lipmp3lame with openshot

[Gary Aitken]

I'm trying out openshot to learn something about video editing.
When I go to export, it claims:
 "The following codec(s) are missing from your system:
 libmp3lame"

The openshot executable is statically linked, and there is a libmp3lame.a
in /usr/local/lib, as a result of installing multimedia/gstreamer-ffmpeg,
I think.

Anyhoo, it's not clear to me exactly what the problem is, or how to go about
finding out.  I presume it is trying to dynamically load the library, or
trapping an unresolved reference.  I'm pretty rusty on ar and ld, so any
hints would be appreciated.

Gary