MailItem Find method doesn't work

[Cmon]

I'm using outlook interop version 11. The outlook is 2003. The code is in c# .net, console application. It works on my computer, but when I put it on the server, it can't read the mailitem.
When I tried it on the server, I can find all of the item that fits with the filter., say, I found 3 emails out of 20000 emails.

When I use

oUnreadMailItem = (MailItem)oItems.Find(sFilterInbox);

It can't find the email that I'm looking for.

If I use

oUnreadMailItem = (MailItem)oItems[1];

I can find the email.

Some part of the code:

                String sTotalEmail = oInboxFolder.Items.Count.ToString(); 
                String sFilterInbox = "@SQL=\"urn:schemas:httpmail:read\"=0 and \"urn:schemas:httpmail:subject\" like '%" + sSubjectEmailPattern + "%' and \"urn:schemas:httpmail:fromemail\" like '%" + sEmailSenderPattern + "%' "; 
                putMessage("Filter: " + sFilterInbox); 
                oInboxFolderItems = oInboxFolder.Items.Restrict(sFilterInbox); 
                oInboxFolderItems.Sort("ReceivedTime", true); 
                if(oInboxFolderItems.Count > 0) 
                    dtLastReceivedTime = ((MailItem)oInboxFolderItems[1]).ReceivedTime; 
                String sCount = oInboxFolderItems.Count.ToString(); 
                putMessage("Found " + sCount + " " + CheckReFaxOn.ToString() + " message(s) out of " + sTotalEmail + " email(s)."); 
                Items oItems = oInboxFolder.Items.Restrict(sFilterInbox); 
                iTotalEmailNeedToBeCheck = oItems.Count; 
                oUnreadMailItem = (MailItem)oItems.Find(sFilterInbox); 
                MailItem oMailTest = null; 
                while(oUnreadMailItem != null) // this works on my computer but it won't work (always null) on server 
                { 
                // do something 
                }

It only happens on the server. It will do fine on my computer.
Any idea why?

Also when I loop through the mails on the inbox, it will only loops half way.

sFilterInbox = "[UnRead]=true"; 
foreach(MailItem Item in oInboxFolder.Items.Restrict(sFilterInbox)) /// read unread only 
{ 
  //if(something) 
  //  mark as read 
  //else 
  //  continue 
}

Example: I found 5 unread email. It will read the first 3.
This happens only when I mark the email as read. Any idea how to loop the proper way?
Thanks.