not able to root

[chmielpiotr]

I have 2 Samsung Galaxy S2 from T-Mobile.
I rooted first phone with no problems using this guide. Then I installed CyanogenMod 10.2 and it works great.
I've been trying to root the other phone for the last 2 hours and I have some problems.
Right now there is SuperUser app on the phone but apps like Titanium Backup or Root checker show me that phone is not rooted.
First I was using TWRP and it reads SD card so I chose to install Superuser 3.1.3 Busybox with success.
After that Titanium Backup or Root checker showed me that my device is not rooted.
Then I did all steps one more time. No difference.
Then I tried to use ClockworkMod Touch but not only I didn't success but I was stopped at the beginning because ClockworkMod can't mount SDCard.
So I did all steps one more time with TWRP.

Did I fail to follow some step?
Or maybe this phone is defective...

Right now I gave it last more chance and I hit to install new rom with wiping all data, cache, sdcard etc...
and...
I'm seeing Cyanogenmod logo loading... so it's ok? I guess...
Anyway, can you still help understanding what was wrong?

 

[Golfdriver97]

The only thing I can think of is perhaps the binaries in the SU app need to be updated? Did you download the most up to date Superuser app version?