Find all solutions to k bishops on chessboard with backtracking

I am trying to solve the puzzle of placing k non-attacking bishops on an 8x8 chessboard. http://mathworld.wolfram.com/BishopsProblem.html What i do is try to place the rook on a square, if However I have some problem in my backtrack method, because I only print the first found solution. The methods finds solutions only for GOAL <= 12, and I know there are is a solution for if that might give any clue...

static final char EMPTY = '*';
    static final char BISHOP = 'B';
    static final int GOAL = 10;

    static void solve(char[][] board, int row, int col, int placed) {
        if (placed == GOAL) {
            printSolution(board);
            return;
        }

        if (col == board.length) {
            col = 0;
            row++;
            if (row == board.length) {
                return;
            }
        }

        if (isSafe(board, row, col)) {
            board[row][col] = BISHOP; // PLACE BISHOP
            solve(board, row, col + 1, placed + 1);
        } else {
            solve(board, row, col + 1, placed);
            return;
        }
        board[row][col] = EMPTY; // BACKTRACK
    }

here is the output when calling solve(board, 0, 0, 0)

 B  B  B  B  B  B  B  B 
 *  *  *  *  *  *  *  * 
 *  *  *  *  *  *  *  * 
 *  *  *  *  *  *  *  * 
 *  *  *  *  *  *  *  * 
 *  *  *  B  B  *  *  * 
 *  *  *  *  *  *  *  * 
 *  *  *  *  *  *  *  *