Hello & welcome from Canada. Glad to have you here. I checked your website - good looking pack you have & though I don't read your language, I truly enjoyed the photos.
Bungwa has a very dry mouth and I only managed to get a very tiny white patch on the test card but it was still sufficient to do the test with that. It only turns white when it's dry - the instructions are quite explicit. Of course as Pat says it could be a bad test form.
Welcome! This is a great forum to gather information on. Im sure you will be able to find the answers to many questions you may have along with some "b" friends.