There are two things that can be happening - you either messed up in creating your submission or more likely your validation set is not representative of the test set.
From what I hear about the competition, likely it is the latter but don’t take my word for it
Here is the ultimate resource imo on learning about the train - val - test splits. http://www.fast.ai/2017/11/13/validation-sets/
I don’t mean to sound like a dumb ass (saying this normally preceeds people sounding like a dumb ass so please accept my apologies for indeed being a dumb ass ) but in the future would you be so kind please and create a separate thread or find a thread which already discusses what you want to ask about? I am sure happy to help, but as it is right now, what we are discussing here has nothing to do with the original intent of this thread and it will make using this forum much harder and annoying for people who come here in the future
Many thanks and once again please accept my apologies! Hate to be the thread police but maybe via slightly better house keeping we can all make this forum even more useful to others