Validates_format_of date

Can someone tell me why this returns ‘dob is invalid’ when dob is

validates_format_of :dob, :with => /[0-9]{2}.[0-9]{2}.[0-9]
{4}/, :message => ‘is invalid’

I’m trying to validate a date entred into a form. I suppose there are
different ways to accomplish this, and because it doesn’t work, I’m
going to be using them, but this seems like a basic format that should

irb gives me this:

“01/01/2007” =~ /[0-9]{2}.[0-9]{2}.[0-9]{4}/
=> 0

“01/01/2007” =~ %r{[0-9]{2}/[0-9]{2}/[0-9]{4}}
=> 0

“01/01/2007” =~ %r{^[0-9]{2}/[0-9]{2}/[0-9]{4}$}
=> 0

none of these combinations work in validates_format_of.

Ideas? Things to try?

Mike B.