Hiding UITableView separator behind the contentView

Question

I made a grouped UITableView in iPhone OS 3.0 that looked like the left image. The result is the right image in OS 3.1. (I'm new so I can't use the 'img' tag...)

http://i283.photobucket.com/albums/kk295/gcampagna/Capturedcran2009-09-15205242-1.png

The imageView is under the separators.

I've tried to put the content view in front. The separatorStyle propriety seems ignored when the tableView is in grouped style (to draw the separator myself). Changing the separator color gives strings results.

Thanks for your help!

Edit: This is the code with no change made :

static NSString *CellIdentifier = @"Cell";

UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
 cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
 cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
 cell.textLabel.font = [UIFont boldSystemFontOfSize:18.0];
}

cell.textLabel.text = [[metro.arretDirection objectAtIndex:indexPath.row] name];

NSString* name;
if (indexPath.row == 0) {
 name = @"Begining";
}
else if (indexPath.row + 1 == [metro.arretDirection count]) {
 name = @"End";
}
else {
 if ([[[metro.arretDirection objectAtIndex:indexPath.row] lines] count]== 1) name = @"Little";
 else name = @"Big";
}

UIImage* metroImage = [[UIImage alloc] initWithContentsOfFile:[[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:[NSString stringWithFormat:@"%i%@.png", metro.metroNumber, name]]];
cell.imageView.image = metroImage;
[metroImage release];

return cell;