I've been struggling to see why it didn't work, assuming both brake sections are block separators you have enough blocks to make it work. (Maybe not safely, but it should at least launch the train.
Finally, I see why it doesn't work. You have 1 brake section in 2 parts, but you didn't completely split the brake run into 2 separate parts. You are using 3 section separators so the end of one section is the same as the beginning of the next. There is no block segment between them. Add another section separator and it will work (provided the first brake section can safely stop the train). Even if they bump against each other, both brake sections need their own beginning and end section separator to have block between them.
You have:
| brake | brake |
You need:
| brake | | brake |