return greatest date in rows meeting criteria

Perhaps you should manually prepare a sample of what your actual data looks like. It is difficult to determine how your data is formatted, what is included in your data. With out some sample data that is representative of your actual data, it will be difficult to provide you with a viable solution.

Attach a sample workbook. Make sure there is just enough data to make it clear what is needed. Include a BEFORE sheet and an AFTER sheet in the workbook if needed to show the process you're trying to complete or automate. Make sure your desired results are demonstrated, mock them up manually if needed. Remember to desensitize the data.

Click on GO ADVANCED and use the paperclip icon to open the upload window.

View Pic