asp.net mvc blunder - bad il format

i'm following clicking run visible studio (~14:00 min video) i'm removing following blunder summary browser:

server blunder '/' application.

bad il format.
description: an unhandled difference occurred during execution 
current webrequest. greatfully hearing smoke-stack snippet some-more information 
about blunder andwhere originated code.

exception details: system.badimageformatexception: bad il format.

source error:

line 12:         ' (2) url parameters
line 13:         ' (3) parameter defaults
line 14:         routes.maproute( _
line 15:             "default", _
line 16:             "{controller}/{action}/{id}", _


source file: c:\users\...\tasklist\tasklist\global.asax.vb    line: 14

stack trace:

[badimageformatexception: bad il format.]
   vb$anonymoustype_0`3..ctor(t0 controller, t1 action, t2 id) +0
   tasklist.mvcapplication.registerroutes(routecollection routes) in
    c:\users\...\tasklist\tasklist\global.asax.vb:14
   tasklist.mvcapplication.application_start() in
    c:\users\...\tasklist\tasklist\global.asax.vb:23


version information:
   microsoft .net horizon version:2.0.50727.1434;
   asp.net version:2.0.50727.1434 

i've double-checked formula i've typed in, am i missing?

thank you!

versions:

• asp.net mvc beta (16th october 2008)


• visual studion 2008 (9.0.21022.8 rtm)


• vista ultimate sp1


• iis 7.0.6000.16386