Problem With Stored Procedure Parameters

I'm executing a stored procedure with a parameter that is a uniqueidentifier or guid(vb).

When I then try to insert that value into a table, I get the following error....

Incorrect syntax near '-'.

ALTER PROCEDURE [dbo].[mw_Articles_UpdateArticle]
-- Add the parameters for the stored procedure here
@ArticleID INT,
@Title VARCHAR(50),
@Body VARCHAR(MAX),
@ParentID INT,
@UserName NVARCHAR(256) = NULL,
@UserID uniqueidentifier = NULL,
@Importance INT,
@Approved BIT,
@EditNotes VARCHAR(50)
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;

IF EXISTS(SELECT ArticleID FROM mw_Articles WHERE ArticleID = @ArticleID)
BEGIN
PRINT 'FOUND'
DECLARE @CurrentVersion INT
SELECT @CurrentVersion = (SELECT MAX(Version) FROM mw_ArticlesVersions WHERE ArticleID = @ArticleID)
INSERT INTO mw_ArticlesVersions(ArticleID, Version, Title, Body, ParentID, Approved, UserName, UserID, Importance, EditNotes) VALUES (@ArticleID, @CurrentVersion + 1, @Title, @Body, @ParentID, @Approved, @UserName, @UserID, @Importance, @EditNotes)
IF @Approved = 1
BEGIN
UPDATE mw_Articles SET Version = (@CurrentVersion + 1) WHERE ArticleID = @ArticleID
END
END
ELSE
BEGIN
PRINT 'NOT FOUND'
END


END



EXEC@return_value = [dbo].[mw_Articles_UpdateArticle]
@ArticleID = 20,
@Title = N'roooot',
@Body = N'dfgh',
@ParentID = 0,
@UserName = N'1',
@UserID = 66116249-63da-4179-85b4-08fd2fa6a315,
@Importance = sdfg,
@Approved = 1,
@EditNotes = N'sdfg'