I realized several people are experiencing the same issue. Sometimes the bot @photocontests doesn't reply to their post and ignores the submissions to the contest.
After some investigation and also by looking at how other bots work, such as @banjo and @cleverbot, I understood why.
@photocontests is not the only bot... there are a few of them:
https://steemd.com/@photocontests
https://steemd.com/@photocontests2
https://steemd.com/@photocontests3
https://steemd.com/@photocontests4
... and apparently, the system assigns a bot to each participant... and in my case, it was number 4.
Now, why didn't he replied to my submissions today? Easy answer, the bot is exhausted and cannot reply, as you can see here: https://steemd.com/@photocontests4
So, I guess I have to wait for "my" bot to have enough power to reply... or else my post has a high chance of being lost.
This is correct! Bots can experience problems with bandwidth, like in your case, or nodes! Nevertheless, all entries are being looked through manually by @juliank! It is a manual selection of images!!! So don't worry if you are not getting a comment, you are still participating!