xp_logevent Invalid Parameter Type
From the xp_logevent topic in the documentation:


  ' message '
  Is a character string with a maximum of 2048 characters.


So, I would change this:

Declare @message nvarchar(max);


To this:

Declare @message nvarchar(2048);


Or possibly even non-Unicode (the docs aren't clear):

Declare @message varchar(2048);


Also, severity should be delimited as a proper string (in spite of the terrible example in the docs), and in upper case (in case it matters on a case-sensitive collation, who knows what those cowboy XP coders might have done):

EXEC master.sys.xp_logevent 60000, @message, 'INFORMATIONAL';


Your CLR procedure is not relevant here...