What period and year are in the PO Options screen. How many days to retain completed PO's is it set for in that screen as well? Typically those purge from PO entry from a period end process if the days to retain completed is met.

Since the underlying databases were improved such that the "two bucket" system was eliminated throughout most of 4.5, and things would post in the correct history period even if closed later, we have often left P.O. and A.P. open to avoid losing important history.  

So I guess my question is, are you saying that PO history does not work like SO history?  It is not designed to just move closed POs into history, and it only moves them after days the days to retain is passed and period end is run?

I reread your original post. Do you have the check box selected in PO>Setup>Options History tab Retain PO History?  If this check box is selected after being previously cleared, and data exists in the purchase order data entry files, a message asks if you want to create purchase order history using the Create Purchase Order History utility.

The box is checked.  I tried to uncheck it and received an error message "The column is not in the IOList."..  I stays unchecked, but if I accept the options and come back in, it's still checked.   I've tried to run the Create Purchase Order Utility manually but it fails.  

Again though, do you know if PO history works the same or similar to SO history?

Good news!  I figured it out.  What I did was rename my po data directory, and then I activated the module again, making it create new files.  Then I went through the setup wizard.  When that was finished, I copied the options file from the new po data folder to the old po data folder, then swapped it back in.  This time Iw as able to go in to options, uncheck retain history, save, go back and check retain history and tada!  It worked and it populated my history files! 

Thanks for your help!