No more tethering after Jailbreak?

Hi guys, after a long battle I managed to upgrade my unlocked/jailbreaked iphone 3G to iOS 4.1 (without changing the baseband - i used Pwnage Tool 4.1.2 and ultrasn0w). I have now reception with my German carrier and everything is great, BUT whenever I try to tether with that iPhone (either USB or Bluetooth) the screen flashes and then only shows the pineapple. What do I have to do to make it work again? (After the initial jailbreak/unlock 2 years ago with quickpwn the tethering worked just fine).

Thanks!!!

no change in baseband, yet before tethering worked...

.... now all i get is the short flash and then the pineapple. I used a custom made ipsw to not change the baseband with the 4.1 update, so why would the tethering work before the update and not now? Am i missing something?
And what does the flash+pineapple mean?

but i still have the slider for tethering, and can enable it, just the phone goes in pineapple mode as soon as connected to the mac.
does this info make a difference?

installed tetherme - still pineapple mode!

now I installed tetherme - at least i think i did, since I had the tethering-slider before that in settings already, i cannot really tell (how do I check?).
However, when I try to connect the iphone to the mac to tether, same old same old (=pineapple mode).
HELP!

HELP - iphone won't tether anymore!

ok, i need more/still help. i had the tethering slider BEFORE installing tetherme, but did pay and install tetherme, switch on tethering in settings, but as soon as i connect the phone to my mac, it switches to pineapple. WHY? and what can i do? I urgently need my tethering function!!!!

I used pwnage tool 4.1.2 and created an .ipsw version 4.1....