[SQLObject] Unable to set StringCol to be UNIQUE

[luis c. <lo....@gm...>]

Keeps throwing an error in MS SQL Server that this column type is not
capable of being made a key ... is it possible to make this a unique field
in SQL Server?  My code is simple:

class myClass(SQLObject):
    fld_name = StringCol(alternateID=True, unique=True)

Please help.

- Luis