How to search emails in Gnus?

[Marius Hofert]

Hi,

I recently realized that I have (require 'nnir) in my ~/.gnus.el but I am 
missing some nnir-related functions. Do I have to download nnir.el and load it 
or should it come/be installed with Gnus by default?

How do you search for Mails at a specific date, e.g., 2012-03-04?
I tried it with C-u G G, then DATE and "2012-03-04", but it didn't work.

Cheers,

Marius