Queen kill 2d program

pls check the program i write correct one but getting unresolved error

package backstracting;

public class queen2dkill {

public static void main(String[] args) {			  
		queenchange2dkill(new boolean[3][4],2,0,0,0," ");
	}
	public static void queenchange2dkill(boolean[][] deno,int tq,int qsfr,int row,int col,String ans) {
		if(tq==qsfr) {
			System.out.println(ans);
			return;
		}
		if(col==deno[0].length) {
			row++;
			col=0;
		}
		if(row==deno.length) {
			return;
		}
		if(PlaceQueen(deno,row,col))
		deno[row][col]=true;
		queenchange2dkill(deno,tq,qsfr+1,row,col+1,ans+"{"+row+"-"+col+"}");
		deno[row][col]=false;
		queenchange2dkill(deno,tq,qsfr,row,col+1,ans);
			
	}
	public static boolean PlaceQueen(boolean[][] deno,int row,int col) {
		 int r=row-1;
		 int c=col;
		 
		while(r>=0) { if(deno[r][c]) {
			 return false;
		}  r--;
		 }
		r=row;
		c=col+1;
		while(c>=0) {
			if(deno[r][c]) {
				return false;
				
			}
			c--;
			
		}
        r=row-1;
        c=col-1;
        while(r>=0&&c>=0) {
        	if(deno[r][c]) {
        		return false;
        	}
        	r--;
        	c--;
        }
        r=row-1;
        c=col+1;
        while(r>=0&&c<deno.length) {
        	if(deno[r][c]) {
        		return false;
        	}
        r--;
        c++;
        
        return true;
}

}
}

Can you please explain what error you are getting?