Default Rooting Droid X2, permission denied

I'm following this guide to root my Droid X2:
http://forum.xda-developers.com/show....php?t=1234907

It gives some info on things I needed into install, including the Android SDK/related driver, changing my phone's development settings, and a few guides on how to use the SDK.

However, when in the command prompt, I get permission denied as I try to follow the guide. I googled for solutions but everyone else with this problem seems to have already rooted their phone. One other guy also has this problem, and he posted in the Droid X2 forum, but nobody answered.

Anyway, I open the command prompt and type this in:

cd c:\adt\sdk\platform-tools
adb.exe

I am now able to do some commands with my phone, like "adb reboot", the phone listens to me.

But when I do step 3 of the guide, I do this

adb shell
su

I get "permission denied". Help?