Relative Auto-Enter Serial Key

[Ninja]

I need a serial key which only increments based on the uniqueness of another field.

Allow me to explain.

When the record is created the date is entered into the date field. If this is the first record to be entered with this date, the serial key should be 1, the second 2 and so on. As soon as a new date is entered the serial key should revert to 1. An added complication is that the records are not necessarily entered in order of date. any clever ideas?

[-Queue-]

See attached for possible solution. Note that records must be created via the 'New' script in order for the Lookup to work correctly once they are committed (the record is exited).

NinjaSerial.zip