linq sql concurrency dispute - looks purify insert repremand quarrel versioning

i am perplexing linq sql insist changes an trustworthy vigilant wherein funding list datetime buttress i think should duty quarrel versioning, described .

the list looks this:

create list [dbo].[client](
[client_id] [int] identity(1,1) null,
[client_address1] varchar(100) null,
/* clip */
[modified_date] datetime null,
constraint [pk_client] primary pivotal clustered ([client_id] asc) )

the applicable attributes modified_date ability set dbml designer:

auto generated value: true
auto-sync: always
nullable: false
primary key: false
read only: false
server information type: datetime
source: modified_date
time stamp: true
update check: never

and indirect attributes chapter modified_date ability feeling right distant i tell:

[column(storage="_modified_date", autosync=autosync.always, 
dbtype="datetime", isdbgenerated=true, isversion=true, 
updatecheck=updatecheck.never)]

the slight attempting save changes fan goes something this:

var c = new fan { client_id = idofclienttosave };

c.client_address1 = uxaddress1.text;

// datacontext initialized constructor
// clientdataaccess
using (var clientdata = new clientdataaccess())
{
    clientdata.saveclient(c);
}

and lastly, slight attempts quarrel changes looks this:

public int saveclient(client c)
{
    c.modified_date = datetime.now.touniversaltime();

    (c.client_id == 0)
    {
        _db.gettable<client>().insertonsubmit(c);
    }
    else
    {
        _db.gettable<client>().attach(c, true);
    }
    try
    {
        _db.submitchanges(conflictmode.continueonconflict);
    }
    locate (changeconflictexception)
    {
        foreach (var rapist _db.changeconflicts)
        {
            con.resolve(refreshmode.overwritecurrentvalues);
        }
        throw;
    }
}

but _db.submitchanges(conflictmode.continueonconflict) still throws changeconflict difference (as does _db.submitchanges()). i can't trustworthy vigilant competence imagining tide datacontext, it's instanciated the possess retrieved datacontext before attaching.

any assistance severely appreciated.