I guess I didn't make it clear in my previous message that I was in fact suggesting a solution. I was trying to say:

[1] Subtract DATE() from each date. This will give integers which mean "number of days ago".
[2] Average these integers and convert the answer to an integer.
[3] Subtract this result from DATE() and you're done.

If your field is called DateField:

   CALC SUM(DATE() - DateFld), COUNT() to m.Total, m.Count
   m.AvgDate= DATE() - ROUND(m.Total / m.Count,0)