Need help with Connect 4 game, IndexOutOfRangeException was unhandled

Question

Hi! I've been struggling with this for a while now, the issue is that as soon i move a game piece to the field i get this errorats "IndexOutOfRangeException was unhandled" and i don't know why since my intention with the code was to use for loops
look through the 2D array thats based on two constants: BOARDSIZEx = 9 and BOARDSIZEy = 6. Instead of traditional 7*6 connect 4 grid i made it 9 squares wide due to having pieces on the side to drag and drop.
Here's the code for my checkwin:
public bool checkWin(Piece[,] pieceArray, bool movebool)
bool found = false;
//Horizontal
for (int i = 0; i < BOARDSIZEx - 3; i++)
for (int j = 0; j < BOARDSIZEy; j++)
if ((pieceArray[i, j] != null)
&& (pieceArray[i, j] == pieceArray[i, j + 1])
&& (pieceArray[i, j] == pieceArray[i, j + 2])
&& (pieceArray[i, j] == pieceArray[i, j + 3]))
if (pieceArray[i, j].IsStarter != movebool)
found = true;
goto Done; //interesting way of getting out of nested for loop
//for more on goto: http://stackoverflow.com/questions/324831/breaking-out-of-a-nested-loop
//Vertikal
for (int i = 0; i < BOARDSIZEx; i++)
for (int j = 0; j < BOARDSIZEy - 3; j++)
if ((pieceArray[i, j] != null)
&& (pieceArray[i, j] == pieceArray[i + 1, j]) && (pieceArray[i, j] == pieceArray[i + 2, j])
&& (pieceArray[i, j] == pieceArray[i + 3, j]))
if (pieceArray[i, j].IsStarter != movebool)
found = true;
goto Done; //interesting way of getting out of nested for loop
//for more on goto: http://stackoverflow.com/questions/324831/breaking-out-of-a-nested-loop
//Diagonal, Lower left to upper right
for (int i = 0; i < BOARDSIZEx - 3; i++)
for (int j = 0; j < BOARDSIZEy - 3; j++)
if ((pieceArray[i, j] != null)
&& (pieceArray[i, j] == pieceArray[i + 1, j +1])
&& (pieceArray[i, j] == pieceArray[i + 2, j + 2])
&& (pieceArray[i, j] == pieceArray[i + 3, j + 3]))
if (pieceArray[i, j].IsStarter != movebool)
found = true;
goto Done; //interesting way of getting out of nested for loop
//for more on goto: http://stackoverflow.com/questions/324831/breaking-out-of-a-nested-loop
//Diagonal, upper left to lower right
for (int i = 0; i >= BOARDSIZEx; i--)
for (int j = 0; j < BOARDSIZEy - 3; j++)
if ((pieceArray[i, j] != null)
&& (pieceArray[i, j] == pieceArray[i - 1, j + 1])
&& (pieceArray[i, j] == pieceArray[i - 2, j + 2])
&& (pieceArray[i, j] == pieceArray[i - 3, j +3]))
if (pieceArray[i, j].IsStarter != movebool)
found = true;
goto Done; //interesting way of getting out of nested for loop
//for more on goto: http://stackoverflow.com/questions/324831/breaking-out-of-a-nested-loop
Done:
return !found;
It's at the vertical check that the error occurs and also my checkwin doesnt seem to respond to the call in the game.cs code.
//check for win
bool moveBool = true; //returns yes or no depending on whether both players have moved their pieces
if (move % 2 == 0) moveBool = false;
bool win = rules.checkWin(pieceArray, moveBool);
//The game is won!
if (win)
string winningPlayerName = player1.Name; //creating a new player instance, just for shortening the code below
if (moveBool == false) winningPlayerName = player2.Name; //if it was player 2 who won, the name changes
message = winningPlayerName + " has won the game!\n\n"; //The name of the player
Board.PrintMove(message); //Print the message
if (moveBool == true) player1.Score += 1; else player2.Score += 1; //update score for the players
//The player's labels get their update texts (score)
Board.UpdateLabels(player1, player2);
//Here, depending on what one wants to do, the board is reset etc.
else
move++; //draw is updated
And here's a picture on how it looks like at the moment.
Thanks in Advance!
Student at the University of Borås, Sweden

Answer 1

for (int i = 0; i < BOARDSIZEx; i++) // If BOARDSizex is the number of elements in the first dimension...
for (int j = 0; j < BOARDSIZEy - 3; j++)
if ((pieceArray[i, j] != null)
&& (pieceArray[i, j] == pieceArray[i + 1, j]) && (pieceArray[i, j] == pieceArray[i + 2, j])
&& (pieceArray[i, j] == pieceArray[i + 3, j])) // Then [i + anything, j] will be out of range.
You probably meant to add the one, two, or three to the j rather than the i.