algorithm - Verify which bubble is connected to top using DFS

I am working on a bubble shooter game in this game i have implemented searching using DFS as suggested in this link, and this is working fine.

Update

Here is my code for DFS

-(void)callDfs:(int)startR:(int)startC:(int)color{

notVisitedBubblesArr = [[NSMutableArray alloc]init];



//reset visited matrix to false.
for(int i = 0; i < R; i++)
    for(int j = 0; j < C; j++)
        visited[i][j] = FALSE;

//reset count
count = 0;
isFound = NO;

bubbleBlastCount = 0;
[self dfs:startR :startC :color :false];

[self bubbleFalling];


}
-(void)dfs:(int)ro:(int)co:(int)colori:(BOOL)set{
    coundown++;
    for(int dr = -1; dr <= 1; dr++)

        for(int dc = -1; dc <= 1; dc++)
            if([self ok:ro+dr :co+dc]) // 4 neighbors
            {
                int nr = ro+dr;
                int nc = co+dc;

                if ((([[[bubbles_Arr objectAtIndex:nr] objectAtIndex:nc]   integerValue]==colori) && !visited[nr][nc])) {
visited[nr][nc] = true;
count++;
[self dfs:nr :nc :colori :set];

if(count>2)
{
// pass row and colom will start dfs
//  if (nr >= touchClum && nc >= touchROW) {
isFound = YES;
bubbleBlastCount++;
[[bubbles_Arr objectAtIndex:nr] replaceObjectAtIndex:nc withObject:NOCOLOR];
[bubbles[nc+1][nr+1] setTexture:[[CCTextureCache sharedTextureCache] addImage:@"blank.png"]];
}
}

}
}

Now i am trying to implement bubble falling using DFS, i studied this link. i got all unvisited nodes after DFS but i am not able to verify with node is connected to top.

Here is my code for bubble falling

-(void)bubbleFalling{

for(int i = 0; i < R; i++){
    for(int j = 0; j < C; j++){    
if (!visited[i][j]) {

    //NSLog(@"Array :  %d %d", i,j);

    NSLog(@"Value : %d",[[[bubbles_Arr objectAtIndex:i] objectAtIndex:j] integerValue]);

    BOOL canReach = [self canreachTop:i :j];
    if(canReach){
        NSLog(@"Yes");


    }

    else{
        NSLog(@"NO");
        [[bubbles_Arr objectAtIndex:i] replaceObjectAtIndex:j withObject:NOCOLOR];
        [bubbles[j+1][i+1] setTexture:[[CCTextureCache sharedTextureCache] addImage:@"blank.png"]];
    }

}


    }

}
}

-(BOOL)canreachTop:(int)ro:(int)co{
   int topNode = [[[bubbles_Arr objectAtIndex:R-1]objectAtIndex:C-1] integerValue];

BOOL success = FALSE;
for(int dr = -1; dr <= 1; dr++)
    for(int dc = -1; dc <= 1; dc++)


        if([self ok:ro+dr :co+dc]) // 4 neighbors
        {
            int nr = ro+dr;
            int nc = co+dc;

            if ((([[[bubbles_Arr objectAtIndex:nr] objectAtIndex:nc] integerValue]== topNode) && !visited[nr][nc])) {
            success = TRUE;
            }
        }


return success;
}


-(BOOL)ok:(int)r:(int)c{
    return r >= 0 && r < R && c >= 0 && c < C;
}

Below is the screenshot of my iPhone simulator in that green bubble should fall because it is not connected with any bubble, i think we have to check whether it is connected with the top bubble or not or i have to follow some other approach?

This is my first game and i am not getting what is wrong with my bubble falling code.

Thanks in advance.