Can't update nulable column with NULL value to overwrite some value

Question

Hi, I have a subsonic version 2.2.0.0. I have a SQL Server 2005 table "Items" with column

CategoryId uniqueidentifier null.

For this table Subsonic has generated a class with property Guid? CategoryId First I insert an record with some valid CategoryId value. Next I try to update (set to NULL) CategoryId of same record

item.CategoryId = null;

• the intercepted SQL statement by SQL Profiler does not include directive for this column to set NULL. So the problem is - this column can't be reset to NULL if someone has previosly assigned value to such column.