I think you need a line like:

dc.tblUsersInApplications.InsertOnSubmit(uia);

>Yes
>
>>Do you have a primary key identified for the table in SQL Server?
>>
>>
>>>Why doesn't this work????
>>>
>>>

>>>using (AppSecurityDataContext dc = GetDataContext())
>>>{
>>>    tblUsersInApplication uia = new tblUsersInApplication
>>>    {
>>>        UserId = um.UserId,
>>>        ApplicationId = LoginCredentials.ApplicationId,
>>>        LastLoginDateTime = DateTime.Now
>>>    };
>>>
>>>    try
>>>    {
>>>        dc.SubmitChanges();
>>>    }
>>>    catch (Exception e)
>>>    {
>>>        Error = e;
>>>    }
>>>}   
>>>

>>>
>>>I get no exceptions. Runs fine. The date/time doesn't show up in the SQL table after it runs.