Using uniqueidentifier as primary key

[Ernie]

I'm having a problem linking forms when the table in a SQL database uses a
uniqueidentifier as primary key. Access doesn't seem to return the
uniqueidentifier value to use as criteria for the called form to filter with.
Here is the code I am using.

tblconcernarea_sub_catID is a uniquieidentifier field type in both tables.

Dim stDocName As String
Dim stLinkCriteria As String

stDocName = "frm_tblconcernarea_sub_cat2"

stLinkCriteria = "[tblconcernarea_sub_catID]=" &
Me![tblconcernarea_sub_catID]
DoCmd.OpenForm stDocName, , , stLinkCriteria

This is what I see in Visual basic on error:

: stLinkCriteria : "[tblconcernarea_sub_catID]=???????h" : String

Can I not use a uniquieidentifier type field in link criteria or am I doing
something wrong?