Object of type 'System.Boolean' cannot be converted to type 'System.SByte'

I've got a MySQL db with a table created using the following script :

CREATE TABLE IF NOT EXISTS `Sessions` (
       SessionId INT(11) AUTO_INCREMENT NOT NULL,
       SessionUserId INT(11) NOT NULL,
       SessionUserTypeId INT(11) NOT NULL,
       SessionGUID VARCHAR(38) NOT NULL,
       SessionIP VARCHAR(38) NOT NULL,      
       SessionActive BOOLEAN NOT NULL,
       SessionAuthenticated BOOLEAN NOT NULL,
       SessionLastActivityTime DATETIME NOT NULL,
       CONSTRAINT `Session_Users` FOREIGN KEY (SessionUserId) REFERENCES `Users` (UserId),
       CONSTRAINT `Session_UserTypes` FOREIGN KEY (SessionUserTypeId) REFERENCES `UserTypes` (UserTypeId),      
       PRIMARY KEY (SessionId)
) ENGINE = INNODB;

In my data access layer I have a function that looks like this :

void func(SessionDto session)

{

     (...)

     Session x = uow.Sessions.Where(s => s.SessionGuid == session.SessionGuid).Single();

     (...)

}

The highlighted line results in an exception with the following message :

+        $exception    {"Unable to materialize field [SessionActive] on type [ModularEnergy.Server.DAL.Session]. Check your table has an Id column and that your mappings are correct. See inner exception for details. "}    System.Exception {Mindscape.LightSpeed.LightSpeedException}

+        InnerException    {"Object of type 'System.Boolean' cannot be converted to type 'System.SByte'."}    System.Exception {System.ArgumentException}

What's wrong I thought boolean-sbyte thing was covered ?

The SessionActive property in your model is defined as SByte.  You need to change it to Boolean to be consistent with the SessionActive database column.

We did have a bug where TINYINT(1) columns in MySQL would be inferred by the designer as SByte instead of Boolean (though I'm surprised to see this issue occurring with columns *declared* as BOOLEAN, even though BOOLEAN is a synonym for TINYINT(1)).  This has since been fixed as far as we know (see http://www.mindscape.co.nz/forums/Thread.aspx?PostID=9512 for more info).  If you can reproduce the designer inference issue with current nightlies then please let us know and we'll investigate further.

That worked, cheers!