Postcards send from Czech Republic never delivered

Hello postcrossers,

I need help/info from someone from Cz, Pilsen. I sent around 10 postcards from Pilsen on October 1st, some private, some via Postcrossing in travel mode, and none arrived. Do you have some info on what could go wrong? Did your postcards sent during that period arrive?

Thank you!

I am going to Pilsen tomorrow.

Did you put it in a mail box? Do you remember where it was?
What kind of stamps did you use? Was it enough.

I hope I will have a chance to get to a post office (probably in the city centre), so I may ask there.

Send me a PM and give me some details about the cards.