Application.OnTime Not Working for me

What I would like to do is automatically run a macro that displays a reminder (message box) to save and close the workbook the user is in by 3:40pm (assuming they have it open). Here is the code I'm using:

Sub SetAlarm()
Application.OnTime TimeValue("03:40:00"), "DisplayAlarm"
End Sub

Sub DisplayAlarm()
MsgBox "Please Save and Close Your Workbook by 3:40pm!"
End Sub

I can't get this to work at all! The Sub DisplayAlarm works if I run it manually so I know that's not the problem. I haven't been able to successfully get the Application.OnTime event to run at all. I've tried testing it with various times and it doesn't seem to do anything. I don't understand why it wouldn't work for me. I'm using Excel 2010 on Windows 7 Enterprise Service Pack 1.

Please help! Thanks!

Trey

I knew I would make a typo in posting my thread. Regardless...ignore the time in the first sample I gave. I was testing the code this morning and I couldn't get it to work. Here is a better example of what I was experimenting with this morning:

Sub SetAlarm()
Application.OnTime TimeValue("09:55:00"), "DisplayAlarm"
End Sub

Sub DisplayAlarm()
MsgBox "Please Save and Close Your Workbook by 10:00am!"
End Sub

This wasn't working at all. I would watch my windows clock go strike 9:55:00 am and nothing would happen. (I kept the file open)

No, that doesn't work for me either. I tried it:

Sub SetAlarm()
Application.OnTime Now + TimeValue("00:00:15"), "DisplayAlarm"
End Sub

Sub DisplayAlarm()
MsgBox "Please Save and Close Your Workbook by 3:40pm!"
End Sub

I waited about 20 minutes and nothing happened. I'm not sure what to do now.