Ok, so escalating online is nonsense in my opinion. The only objective when chatting online is to get the girl to go on a date with you. You don't need to compliment her and you don't have to make her feel anything for you. All that happens when you meet. That's when you have your chance to make her feel that you're worth it.

With regards to why they don't contact you again: if they friendzone you, it doesn't mean that they want to be friends with you. It means that they don't think that you're sexually worth pursuing. And that is normally because you fail to escalate. There are lots of tutorials on the internet on how to do all this. Or you can get a mentor for about EUR3000 and they will fix this problem forever.
I learned all this very quickly and have reached a high level of confidence when I go on dates. It is definitely doable.