Why would Outlook not return a notification on trying to recall a message?

The conditions under which an email recall will work are very narrow and almost impossible to meet. From the fact that you have not received the notification, it is quite clear that the recall has failed.

From In Microsoft Outlook, how can I recall, replace, or resend a message?

If you accidentally send an incorrect message, the simplest solution may be to send a second, revised version. In some circumstances, you may also be able to recall the message, or replace it entirely. This will work only if:

• The recipients use your Exchange server as their email address, and have not forwarded their Exchange email to another account.
• The recipients are currently logged into their Exchange accounts and using Outlook.
• The message is still unread and remains in the recipients' Inboxes.

Note: When you recall a message, the recipient will receive notification that you are recalling a message.

If the recipient has already opened your email, recall will of course fail. The recipient may also need to authorize the recall, which with natural human curiosity and the aversion to authorizing somebody else deleting mail from their own mailbox, simply will not happen.

For the full details about whether recall will work or not, see in How message recall works the section "Will my recall be successful?". After reading it, you may agree that the recall feature is next to useless. It is better to verify the message 10 times before sending, rather than relying upon recall.

Did you check the "Tell me if recall succeeds or fails for each recipient" box?

The full process is described here (the determination if it succeeded or failed)

http://office.microsoft.com/en-us/outlook-help/how-message-recall-works-HA001091760.aspx

Though - if you didn't click the box (or unclicked it) - there is no way to tell if it worked.