it looks like you were adding seats to the already built stadium parts (100 level sidelines) and not constructing new sections. you have 10000 seats which is the max for 100 level sidelines. Normally you don't want to add seats until new sections are built.
https://glb.warriorgeneral.com/game/stadium.pl?team_id=363on this page, there should be options under 100 corner, 100 endzone, etc to "build section" it will give you a cost and tell you how many seats each new section will come with. You can add seats after the stadium is built, or wherever you have extra money in your budget along the way.
I highly recommend this link for building your stadium :
https://glb.warriorgeneral.com/game/forum_thread.pl?thread_id=4448226also :
Originally posted by Abbaddon
I spent money to add sections for this season, even taking out a loan to be able to pay the players etc. Still no sections added.
Is there a stadium bug or something? Stadium section upgrades are only done from rollover from 1 season to the next. If you didn't click "build section" before season 87 turned into season 88, it won't build these new sections until the 88-89 rollover.