Why do I get an error message from the bittorrent tracker?

Hi! I like to download and seed my LibreOffice builds but I noticed I get the following error message from the tracker most of the time:

Failure: Your client’s “key”
paramater and the key we have for you in our database do not match

I’m using Bittorrent 7.4.2 on MacOS 10.10.1

Does anyone know what it means and what to do&

Thank you very much!