Autofilter Macro Works On One Column, But Not The Other

I'm using Excel to map automotive parts to vehicle applications (two different spreadsheets) for importation into a relational Access database. Production dates for parts rarely match the on-sale dates of the cars, so I've set up a macro that:

1. copies the start production date for a part record into the vehicle workbook at the top of the 'discontinued' column,
2. copies the end production date for the part into the vehicle workbook at the top of the 'release' column,
3. uses these pasted data points as criteria for the autofilter in the vehicle workbook as 'vehicle release date' < 'part end production date' and 'vehicle discontinued date' > 'part start production date'.

I find that the macro works perfectly in the autofilter for the vehicle discontinued date, but not for filtering the vehicle release date. The date is copied and pasted OK. When I check the custom filter dialogue box, the date has been entered in with the 'is less than' menu item selected, but it doesn't bring up any records unless you click on the 'OK' button once the dialogue box is open. I want to run the macro without having to run the autofilter manually at all. To troubleshoot the issue, I broke up the macro into two separate macros, one for release and the other for discontinued. Problem remains, even though the only difference between the two macros is the relative cell addresses. I've checked formatting of the cells for text vs. numeric and that doesn't appear to be a problem.