c# - Windows Service not retrieving edited SQL rows -

i tried find answer using search, feel wording poorly decent results.

i have windows service uses linq-sql. should pull data table every 20 seconds, process data, update row accordingly , rinse , repeat.

    sqldatacontext sqldb;      protected override void onstart(string[] args)     {          servicelog1.writeentry("service1 started");          sqldb= new sqldatacontext ();          //initalize , start timer service action         timer timer = new timer();         timer.interval = 20000; // 20 seconds         timer.elapsed += new elapsedeventhandler(this.dowork);         timer.start();     }      public void dowork(object sender, elapsedeventargs args)     {         list<items> items= sqldb.items.where(i=> i.processed == false).take(20).tolist();          if(items.count > 0)             servicelog1.writeentry("processing " + items.count + " queue items.");           //work work...          //set items processed == true          //submit changes db 

my issue (and i'm not 100% sure issue) this:

if run through 3 unprocessed test items, update them processed should. simple test if scenario, if change value of processed 1 item false in sql, service create entry event log saying processing 1 item, item never updated again , processed on every loop.

this seems happen items edited in sql. new items processed normally. can explain me going on here?

as damien_the_unbeliever pointed out in question comments, issue related sqldatacontext keeping objects in memory. needed create new context each time timer elapses.