Return value from a table based on a text field

[brum_rich]

I have created a text field on a form that uses the DateSerial function to return the value of last month e.g. Jul-06.

I have a table that contains months (e.g. Jul-06, Jun-06 etc) and a corresponding numeric value (e.g. 1,2,3).

I have another text box on the same form that I want to display the numeric value in based on the value that has been returned by the DateSerialfunction. What properties/control source should I set for this field? Or do I need to write some VBA?

Any help would be appreciated.