MSNP server responding with 'null'/not responding to TWN token

[tupac]

I'm writing an msn client and I'm currently attempting to log in with my hotmail.com credentials. Everything has worked fine until I sent my TWN token which I received from https://nexus.passport.com.

Here is a sample session:

code:

client>VER 0 MSNP11 CVR0 server>VER 0 MSNP11 client> CVR 1 0x0409 winnt 5.1 i386 MSNMSGR 8.1.0178 msmsgs example@hotmail.com server> CVR 1 14.0.8089 14.0.8089 14.0.8089 http://msgruser.dlservice.microsoft.com/download/7/5/8/758BFCC9-1744-48F7-8162-E0AC1E7BF5C8/en/wlsetup-cvr.exe http://download.live.com/?sku=messenger client> USR 2 TWN I example@hotmail.com server> XFR 2 NS 64.4.34.110:1863 0 64.4.9.254:1863 Connection with 64.4.34.110 established over port 1863! client> VER 0 MSNP11 CVR0 server> VER 0 MSNP11 client> CVR 1 0x0409 winnt 5.1 i386 MSNMSGR 8.1.0178 msmsgs example@hotmail.com server> CVR 1 14.0.8089 14.0.8089 14.0.8089 http://msgruser.dlservice.microsoft.com/download/7/5/8/758BFCC9-1744-48F7-8162-E0AC1E7BF5C8/en/wlsetup-cvr.exe http://download.live.com/?sku=messenger client> USR 2 TWN I example@hotmail.com server> USR 2 TWN S ct=1280158127,rver=5.5.4182.0,wp=FS_40SEC_0_COMPACT,lc=1033,id=507,ru=http:%2F%2Fmessenger.msn.com,tw=0,kpp=1,kv=4,ver=2.1.6000.1,rn=1lgjBfIL,tpf=b0735e3a873dfb5e75054465196398e0

Then I connect to https://nexus.passport.com, get re-directed, send my credentials, and receive a token that looks something like this: t=EwDoAfsBAAA...RfXgE%3d&p=
I then send to following to 64.4.34.110 (the original, unencrypted connection):

code:

USR 3 TWN S t=EwDoAfsBAAA...RfXgE%3d&p=

And I receive a response 'null', but I'm supposed to receive

code:

USR 3 OK example@hotmail.com example%20display%20name 1 0

Any help is greatly appreciated.