No reply arrow/icon shown after replying to messages in Mail.

I've seen a number of discussions on this topic but I still have not found a solution.

When I respond to a message in one of my Google Apps (IMAP) accounts, sometimes it will show the reply arrow/icon next to the original message but most times it will not. The other weird part is that it only happens in one specific mailbox. Other than my iCloud mailbox, I have three Google Apps IMAP accounts, but this specific mailbox is the only one that has these inconsistencies. The only time i can get the arrow/icon to show is when i'm replying to one of my other two Google Apps accounts. The message always goes through, it's just that it doesn't show the reply arrow/icon and it's very frustrating to have to go to the sent mailbox everytime just to see if i have responded to a message.

I'm running Mac OSX 10.7.2. and Mail version 5.1

I've already tried the following to no avail:

Rebuild the maillbox

ReIndex the entire mail.app

Deleted the cache folder in /Library/Caches/Mail

Deleting the mailbox and readding it

Repaired disk permissions and restarted computer