when i want to access team signature on http://boincstats.com/bam/signature.php?type=team, i get and image with "INVALID TEAM-ID"

SILLY ME?

You're not alone. I deleted my BAM-account to get rid of this and created a new one. It doesn't helped.
The reason was that you have to save this team signature only once in your BAM-account .......
And now I have a high BAM-ID and look like a newbie

As usual it works for me but I'll look into this (probably in the weekend, if you're lucky a bit earlier).

I managed to replicate the error.

The simplest solution until I come up with something permanent: Hit the save button. When the page reloads you should see the correct signature, if not, do a hard refresh of the page.

I'll make a change to fix this on first load.

Pfff, making a permanent solution was easier than I thought.

It should work now right away. Let me know if it doesn't.

You can only test this if you have a BAM-account and never saved the signatures before. I think you did this already to test it yourself, elsewhere I have to create a new fake BAM-account. That makes no sense. Perhaps someone else never having saved a (team)signature can try this.

Didn't save the signature before. Got the correct team signature. So it seems ok.