What is the reason of this issue and how to solve this problem?
The superelevation may not have been calculated to compute the superelevation rates per the geometry. You can still work with a superelevation control line which does not have any curve information if you know the stations, rates, and transition lengths by manually inserting point to the superelevation control line. But it may be easier to go through the superelevation calculation so the program can compute it and give you better starting results. Check out this video on editing superelevation in which he goes through the process of calculating and making modifications to the control lines.
For more information about the Road and Site design tools, visit the Road and Site design WIKI at: http://communities.bentley.com/products/road___site_design/w/road_and_site_design__wiki