Don't understand the potential leak
===

I was using the Analyze function in xcode, and I've fixed everything except this one.

I'm wondering what this exactly means of a "potential leak of an object allocated", and it refers to these lines. 

    - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    
    self.type_prod = [[ProductType alloc] initWithNibName:@"ProductType" bundle:[NSBundle mainBundle]];
	
	NSString *prodtitle = [product objectAtIndex:indexPath.row];
    	type_prod.prodtitle = prodtitle;

     etc etc.

At the end of this void I say:

        [[self navigationController] pushViewController:type_prod animated:YES];
    [type_prod release];

So why does it say there is a potential leak if I release it at the end?