I had this problem here is what I did in order...
0> Went to FB under Account -> Account Settings -> Mobile and setup my phone. If you have done this, remove the phone and re-add it. Send the text
etc with conf code, and then test by following the Facebook Mobile (link) and sending a test text to your phone click "Text a link to my phone"
1> Removed the Facebook App, had to go into menu, settings, manage apps etc etc to remove it
2> went to Menu -> Settings -> Accounts and removed my FB account, it
actually took two tries to be successful
3> added a FB account, set it to be my default photo yes.
4> went to the Market and installed the FB App
5> ran the FB App and logged in, no problems