Unable to log onto Access .adp db after creating new db role using sqlserver 2008.

[Equus57]

I recently had to add a new database role for an existing Access.adp database using SQLSERVER 2008. I already have 4 other roles working just fine, but I cannot connect (We use NT Authentication) when using this new role. It bombs out and says that it's "Unable to verify login. Program Aborting". I cannot determine what I am missing. I use the following procedure to verify who's trying log into the database based on the assigned role. For testing purposes, I assign myself to the role I am testing. The schema and role have the same name. In the procedure below, schema 16384 is the SA account.

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
 
ALTER PROCEDURE [dbo].[ProcGetLoggedInUserData]
AS
DECLARE @user varchar(25) 
SELECT @user = substring(system_user, 
    (charindex('\', system_user) + 1), 
    len(system_user)- charindex('\', 
    system_user))
--PRINT @user
SELECT a.name AS UserID,
    UPPER(d.name) AS UserRole, 
    c.per_id, 
    c.per_code
FROM sys.sysusers a, 
    sys.sysmembers b, 
    dbo.TBL_PERSONNEL c,
    sys.schemas d 
WHERE a.uid = b.memberuid
AND a.name = @user 
AND a.name = c.per_login
AND b.groupuid = d.schema_id
AND d.schema_id <> '16384'