Set-PWdocumentState is giving me an error: "Could not load file or assembly 'ClosedXML, Version=0.90.0.0, ..."

Set-PWdocumentState is giving me an error:
"Could not load file or assembly 'ClosedXML, Version=0.90.0.0, Culture=neutral, PublicKeyToken=fd1eb21b62ae805b' or one of its dependencies. The system cannot find
the file specified."

It won't supress ($null = , | Out-Null) but it doesn't prevent the State from being changed....

is there a "secret handshake"? using 1.30.13.0

Thanks!

Bob