Why cant I castle long in this game?

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slingcity
https://chess.com/daily/game/309594094 Like in the title, i feel like i should be able to castle long but the game wont let me! Can anyone figure out why?
Strangemover

The bishop on g5 is attacking the d8 square and the king cannot pass through an attacked square when castling. 

slingcity

okay thank you!!