dbi help required

[Junkone]

D:\Documents and Settings\>irb
irb(main):001:0> require 'dbi'
=> true
irb(main):002:0> conn=DBI.connect('LPM','sm_user','smuser_0496')
DBI::InterfaceError: Invalid Data Source Name
from C:/Ruby187/lib/ruby/gems/1.8/gems/dbi-0.4.5/lib/dbi.rb:
333:in `pars
e_url'
from C:/Ruby187/lib/ruby/gems/1.8/gems/dbi-0.4.5/lib/dbi.rb:
159:in `_get
_full_driver'
from C:/Ruby187/lib/ruby/gems/1.8/gems/dbi-0.4.5/lib/dbi.rb:
145:in `conn
ect'
from (irb):2


can someone point out where i am makeig a mistake. my odbc connection
seems to connect to sql server successfully but i cannot do it from
ruby.