After building a transit tube access, it says there's no tube connected but ... there is
Maybe it a matter of order in the building.
The tube on the left was build for a "long" time.
I've deconstructed a section of this tube to make the crossing. So that is was made quickly, I put it on priority 9. My duplicant bring plastic for the crossing and also the first section above the access. And both were constructed at this moment, but the 2 other tube section and the access were not made.
The acess was build befor the 2 last tube sections. The power line was already made before.
Reloading the game solved the problem.
Don't knwo : see the message.