Pull out the analysis board, play an arbitrary bishop move with the bishop on d1, play an arbitrary move for black. Then drag the king towards the rook and drop on top of the rook. Now you will see that the bishop on d1 was in the way of castling. Got it now?
Can't castle?


After castling that way, the king is on c1 and the rook is on d1.
Here is an explanation from http://en.wikipedia.org/wiki/Chess960
After castling, the rook and king's final positions are exactly the same as they would be in standard chess. Thus, after a-side castling (also called sometimes c-castling) the king is on c-file (c1 for White and c8 for Black) and the a-side Rook is on d-file (d1 for White and d8 for Black). This castling notated as O-O-O and known as queen-side castling in orthodox chess. After h-side castling (also called sometimes g-castling) the King is on g-file and the h-side Rook is on f-file. This move notated as O-O and known as king-side castling in orthodox chess.
http://fb.hosted.chesscomapps.com/analysis.html?id=1679810&sid=qsmqtscnjkeg8gk06hted4ttr3
Hey I couldn't castle in this game and I don't know why. :\
I hadn't moved the rook or the king, yet.

I still cant castle and dont know how to do it, I may be a little thick using this on line chess, so need to be told in plain English. I can play chess to a reasonable level and know how to castle on a board, but on this I am screwed.

In a position where it's legal for you to castle, just move your king two squares over to the side you want to castle - the Rook will automatically jump to the other side of the King.
Here 0-0-0 is mate so just put the King on c1;

You are not allowed to castle out of check, or through check, or into check.
So instead of getting mad, have a read up on the rules of chess.

Another example, I don't trust it will castle, so I don't rely on it any more, but then there other times, my chess intition kicks in and I know it will Castle. I determine each time now if it'll go or not. Perhaps it's the website, something techy, but in the rules of chess, we're saying that the castle is allowed, thank you for the reply, Pulpofeira.

I've never once had an issue with castling when it was legal to do so. Maybe the issue is with the platform you're playing on maybe? Are those last two screen shots from the mobile app?

Another example, I don't trust it will castle
White cannot castle here, it would be illegal.

Another example, I don't trust it will castle, so I don't rely on it any more, but then there other times, my chess intition kicks in and I know it will Castle. I determine each time now if it'll go or not. Perhaps it's the website, something techy, but in the rules of chess, we're saying that the castle is allowed, thank you for the reply, Pulpofeira.
Here, the Ba6 is in the way of castling.
Hi, I'm trying to castle in a game and its not letting me. I was hoping someone could tell me why? I haven't moved the rook or king, nothing is obstructing the castle and I won't cross through check. It's a 960 game but I should be able to still do it and it isn't letting me. Any suggestions? Here is a link to the game if it helps: http://www.chess.com/echess/game.html?id=27884721