Minimum age validation rule

[Journeyman]

I' need an "minimum age" validation rule for my "members table" to become member you must be 18 years old.
I have tried this rule: <=Date()

But it does not work!

How do i create a validation rule that only allows members that are 18 years or older?

tblMembers

Field: Birthdate, Datatype: Date/Time.

Birthdate is written in following format:
yyyy-mm-dd

Greatfull for any help!

Peter

 

[dcx693]

Please do a search on "age" in the forums, you'll find lots of examples.