A big stadium is not enough. You have to make sure that your fans can get to the stadium. If you do not provide parking or public transportation your stadium will remain empty!
You should also pay attention to the condition of your parking lot and public transportation buildings. When the condition goes down, so does the capacity.
Expanding your buildings increases the capacity. The higher you advance in your manager career, the more buildings become available!
Building details (Parking lot):
|Name||Level||Cost STARS/Money||Effect||Career level requirement|
|Small Parking lot||1||30.000 IGM||3000 spectators||5|
|Medium Parking lot||2||420.000 IGM||5200 spectators||9|
|Medium Parking lot (Luxury)||2||210.000 IGM + 300 STARS|
5200 spectators, Reputation +1
|Big Parking lot||3||980.000 IGM||15.800 spectators||23|
|Big Parking lot (Luxury)||3||490.000 IGM + 680 STARS||15.800 spectators, Reputation +1||21|
|Parking garage||4||2.500.000 IGM||34.000||42|
|Parking garage (Luxury)||4||1.250.000 IGM + 1850 STARS||34.000 spectators, Reputation +1||41|
|Big parking garage||5||6.200.000 IGM||60.800 spectators||54|
|Big parking garage (Luxury)||5||3.100.000 IGM +3500 STARS||63.840 spectators, Reputation +1||52|