The train 107 (and others in this line that were deleted for this problem) say there is no route even though everything is operational.
https://www.dropbox.com/s/98dxocze053osim/Low%201850.11.sve?dl=0
Have you checked:
(1) axle load limits of all track;
(2) total weight limit of all bridges;
(3) one way signs;
(4) breaks in continuity of track;
(5) breaks in continuity of electrification (if applicable);
(6) whether any track between the origin and destination is mothballed/degraded?
I managed to fix it by selecting the station again on the timetable. Apparently the train was in reverse schedule (going from the end to beginning) I think so it was conflicting with the one way signals. I think is it. Is this suppose to happen?
That rather depends on exactly how you have everything set up: there is no single answer to that question at that level of generality.