Why can I not castle queenside in this daily game?

Here is the game, on move #10 I was wanting to castle queenside  but it would not let me even though I wouldn't castle into check or out of check, and I havent moved my king.

DO NOT TELL ME WHAT I SHOULD MOVE, THE GAME IS NOT OVER YET!!!

Oh, basically, you cannot castle your king through a check.

You basically cannot castle:

-Into Check

-Out of Check

-Through a Check

You also can't castle through check.

Or, in other words, the square the rook ends up on cannot be attacked.

Note that the Rook is NOT subject to these limitations. You cannot "check" a Rook, so the Rook is allowed to pass freely across attacked squares during castling.

Ok, thx! I didn't know that.